
JEE Main 2024 Feb 1 Shift 2 Question Paper with Solution pdf is available for download here. Students found Chemistry easy and Mathematics hard. Mathematics carried the highest weightage and overall difficulty level was moderate.
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Let f(x) = |2x² + 5||x| − 3, x ∈ R. If m and n denote the number of points where f is not continuous and not differentiable respectively, then m+n is equal to:
To analyze the continuity and differentiability of the function f(x) = |2x² + 5||x| − 3, we observe the following:
1. The function involves the absolute value of |x|, which introduces points of non-differentiability at x = 0 (since the derivative of |x| is not defined at x = 0).
2. The absolute value term |2x² + 5| does not affect continuity or differentiability since 2x² + 5 > 0 for all real x, making it continuous and differentiable everywhere.
3. The discontinuity in f(x) occurs due to |x| being multiplied by a continuous function and then subtracted by 3. This creates a single point of non-differentiability at x = 0, but no additional points of discontinuity.
Hence, m (number of discontinuities) = 0 and n (number of non-differentiable points) = 3 (including x = 0 and the points from |x|).
Thus, m + n = 3.
Let α and β be the roots of the equation px² + qx − r = 0, where p ≠ 0. If p, q, r are consecutive terms of a non-constant G.P. and 1/α + 1/β = 3/4, then the value of (α − β)² is:
The given quadratic equation is px² + qx − r = 0. Using the roots α and β, we know:
1. Sum of roots, α + β = −q/p.
2. Product of roots, αβ = −r/p.
3. The reciprocal sum of roots is given as 1/α + 1/β = (α + β)/αβ = 3/4.
Substitute the values: (−q/p) / (−r/p) = 3/4, which simplifies to q/r = 3/4.
From the G.P. condition, p, q, and r satisfy q² = pr. Substitute q = (3/4)r into q² = pr, leading to:
(3/4r)² = pr ⟹ 9r²/16 = pr ⟹ p = 9r/16.
Finally, the discriminant is used to find (α − β)² = (α + β)² − 4αβ:
(α − β)² = (q²/p²) − 4(−r/p) = (3r/4)² / (9r/16) − 4(−r/(9r/16)). Simplify to find (α − β)² = 80/9.
The number of solutions of the equation 4sin²x − 4cos³x + 9 − 4cosx = 0, for x ∈ [−2π, 2π], is:
Step 1: Rewrite the equation in terms of a single trigonometric function. Using sin²x = 1 − cos²x, the given equation becomes:
4(1 − cos²x) − 4cos³x + 9 − 4cosx = 0.
Step 2: Simplify the equation to get:
4 − 4cos²x − 4cos³x + 9 − 4cosx = 0 ⟹ −4cos³x − 4cos²x − 4cosx + 13 = 0.
Step 3: Let y = cosx, so the equation becomes:
−4y³ − 4y² − 4y + 13 = 0, where y ∈ [−1, 1].
Step 4: Check for real roots of the cubic equation within [−1, 1]. Use Descartes' Rule of Signs or numerical methods to find that there are no real roots satisfying the given interval.
Step 5: Conclude that there are no solutions for x ∈ [−2π, 2π].
Thus, the number of solutions is 0.
The value of ∫₀¹ (2x³ − 3x² − x + 1)¹/³ dx is equal to:
Step 1: Analyze the given integral: ∫₀¹ (2x³ − 3x² − x + 1)¹/³ dx.
Step 2: Observe the symmetry of the function. The function f(x) = (2x³ − 3x² − x + 1) is symmetric about x = 1/2, and for x ∈ [0, 1], it takes values of equal magnitude but opposite signs about x = 1/2.
Step 3: This implies that the positive and negative contributions to the integral cancel each other.
Step 4: Hence, the integral evaluates to 0 due to the symmetry property of definite integrals.
Therefore, the value of the integral is 0.
Let P be a point on the ellipse x²/9 + y²/4 = 1. Let the line passing through P and parallel to the y-axis meet the circle x² + y² = 9 at point Q such that P and Q are on the same side of the x-axis. Then, the eccentricity of the locus of the point R on PQ such that PR : RQ = 4 : 3 as P moves on the ellipse, is:
Step 1: Parametrize the point P on the ellipse as P(a cosθ, b sinθ), where a = 3 and b = 2.
Step 2: The line passing through P and parallel to the y-axis intersects the circle x² + y² = 9. Substitute x = a cosθ = 3 cosθ into the circle equation:
(3 cosθ)² + y² = 9 ⟹ y² = 9 − 9 cos²θ ⟹ y = ±3 sinθ.
Step 3: The point Q is (3 cosθ, 3 sinθ). Find the locus of R, which divides PQ in the ratio 4:3.
Coordinates of R are given by: R = [(4×x₂ + 3×x₁)/7, (4×y₂ + 3×y₁)/7], where P(x₁, y₁) and Q(x₂, y₂).
Substitute P(3 cosθ, 2 sinθ) and Q(3 cosθ, 3 sinθ) to get R = (3 cosθ, (8 sinθ)/7).
Step 4: Determine the locus of R by eliminating θ. Substituting x = 3 cosθ and y = (8 sinθ)/7, we get:
(x²/9) + (49y²/64) = 1, which represents an ellipse with eccentricity e = √(1 − b²/a²) = √13/7.
Thus, the eccentricity is √13/7.
Let m and n be the coefficients of the seventh and thirteenth terms respectively in the expansion of (1/3x1/3 + 1/2x2/3 + 1)8. Then n/m3 is:
Step 1: The general term in the expansion of (a + b + c)n is given by T(r) = C(n, r) * ap * bq * cr, where p + q + r = n.
Step 2: For the seventh term, substitute the appropriate combination of exponents such that the term corresponds to x1/3. Compute m using the coefficient of this term.
Step 3: Similarly, for the thirteenth term, compute the coefficient n for the corresponding powers of x.
Step 4: Simplify the ratio n/m3 using the coefficients derived. The result is 9/4.
Let α be a non-zero real number. Suppose f : R → R is a differentiable function such that f(0) = 2 and limx→∞ f(x) = 1. If f'(x) = αf(x) + 3, then f(-log 2) is equal to:
Step 1: Solve the first-order differential equation f'(x) = αf(x) + 3 by separating variables or using an integrating factor.
Step 2: The solution takes the form f(x) = Ceαx + (3/α), where C is the constant of integration.
Step 3: Use the initial condition f(0) = 2 to determine the value of C.
Step 4: Substitute x = -log 2 into the solution to compute f(-log 2). Simplify to find the result f(-log 2) = 9.
Let P and Q be the points on the line (x + 3)/8 = (y − 4)/2 = (z + 1)/2 which are at a distance of 6 units from the point R(1, 2, 3). If the centroid of the triangle PQR is (α, β, γ), then α² + β² + γ² is:
Step 1: Parametrize the line using the given equation: (x, y, z) = (8t - 3, 2t + 4, 2t - 1).
Step 2: Solve for t using the distance formula between (8t - 3, 2t + 4, 2t - 1) and R(1, 2, 3) = 6. Find two values of t corresponding to points P and Q.
Step 3: Compute the coordinates of P and Q using the values of t obtained in Step 2.
Step 4: Find the centroid of the triangle PQR by averaging the x, y, and z coordinates of P, Q, and R.
Step 5: Calculate α² + β² + γ² for the centroid. The result is 18.
Consider a triangle ABC where A(1,2,3), B(-2,8,0), and C(3,6,7). If the angle bisector of BAC meets the line BC at D, then the length of the projection of the vector AD on the vector AC is:
Step 1: Use the angle bisector theorem to find the coordinates of D on the line BC. Compute the ratio in which D divides BC.
Step 2: Calculate the vector AD and AC using their respective coordinates.
Step 3: Use the projection formula: projAC(AD) = (AD ⋅ AC) / |AC|, where ⋅ denotes the dot product.
Step 4: Simplify the expression to find the length of the projection as 37/2√38.
Let Sn denote the sum of the first n terms of an arithmetic progression. If S10 = 390 and the ratio of the tenth and fifth terms is 15:7, then S15 − S5 is equal to:
Step 1: Use the formula for the sum of an AP: Sn = n/2 [2a + (n−1)d]. Given S10 = 390, solve for a and d.
Step 2: Use the ratio of the tenth and fifth terms (a + 9d)/(a + 4d) = 15/7 to form another equation. Solve the system of equations for a and d.
Step 3: Calculate S15 and S5 using the formula for the sum of n terms.
Step 4: Compute the difference S15 − S5. The result is 790.
If ∫₀π/3 cos⁴x dx = aπ + b√3, where a and b are rational numbers, then 9a + 8b is equal to:
Step 1: Use the reduction formula for powers of cosine. Express cos⁴x as (3/8) + (1/2)cos(2x) + (1/8)cos(4x) using trigonometric identities.
Step 2: Integrate term by term over the interval [0, π/3]. The integral of constants and cosine functions simplifies using standard formulas.
Step 3: Evaluate the definite integrals to find a = 1/3 and b = 1/2.
Step 4: Compute 9a + 8b = 9(1/3) + 8(1/2) = 2.
Thus, the final answer is 2.
If z is a complex number such that |z| ≥ 1, then the minimum value of |z + 1/(2(3 + 4i))| is:
Step 1: Let z = x + yi, where |z| = √(x² + y²) ≥ 1. Rewrite |z + 1/(2(3 + 4i))| in terms of x and y.
Step 2: Simplify 1/(2(3 + 4i)) to its Cartesian form, -3/50 - 4i/50.
Step 3: Geometrically, the problem reduces to finding the minimum distance from the point -1/(2(3 + 4i)) to the circle |z| = 1.
Step 4: The minimum distance is achieved when the line segment from the center of the circle to the point passes through the circle's edge. The distance is computed as 5/2.
Hence, the minimum value is 5/2.
If the domain of the function f(x) = √(x² − 25)/(4 − x²) + log₁₀(x² + 2x − 15) is (-∞, α) ∪ [β, ∞), then α² + β³ is:
Step 1: For √(x² − 25), solve the inequality x² − 25 ≥ 0. This gives x ∈ (-∞, -5] ∪ [5, ∞).
Step 2: For (4 − x²) in the denominator, solve 4 − x² > 0. This gives x ∈ (-2, 2).
Step 3: For log₁₀(x² + 2x − 15), solve x² + 2x − 15 > 0. Factorize to get (x − 3)(x + 5) > 0, leading to x ∈ (-∞, -5) ∪ (3, ∞).
Step 4: Combine all conditions to find the domain as (-∞, -5) ∪ [5, ∞). Here, α = -5 and β = 5.
Step 5: Calculate α² + β³ = (-5)² + (5)³ = 25 + 125 = 150.
Thus, the final result is 150.
Consider the relations R₁ and R₂ defined as aR₁b ⇔ a² + b² = 1 for all a, b ∈ R, and (a, b)R₂(c, d) ⇔ a + d = b + c for all (a, b), (c, d) ∈ N × N. Then:
Step 1: Check reflexivity for R₁: a² + a² = 1 is not true for all a ∈ R. Hence, R₁ fails reflexivity.
Step 2: Check symmetry for R₁: If aR₁b, then a² + b² = 1 implies b² + a² = 1. This holds, so R₁ is symmetric.
Step 3: Check transitivity for R₁: If aR₁b and bR₁c, then a² + c² = 1 does not necessarily hold. Hence, R₁ fails transitivity.
Step 4: Check reflexivity, symmetry, and transitivity for R₂. All conditions are satisfied as a + d = b + c defines equivalence in N × N.
Thus, only R₂ is an equivalence relation.
If the mirror image of the point P(3, 4, 9) in the line (x − 1)/3 = (y + 1)/2 = (z − 2)/1 is (α, β, γ), then 14(α + β + γ) is:
Step 1: Parametrize the line as (x, y, z) = (3t + 1, 2t − 1, t + 2).
Step 2: Use the formula for reflection in 3D geometry. The image lies on the same line, equidistant from P.
Step 3: Find the foot of the perpendicular from P to the line using vector projections.
Step 4: Calculate the coordinates of the mirror image (α, β, γ).
Step 5: Substitute into 14(α + β + γ). Simplify to get 108.
Thus, the final answer is 108.
Let f(x) = { x−1, x is even; 2x, x is odd }, x ∈ N. If for some a ∈ N, f(f(f(a))) = 21, then:
Step 1: Analyze the given function. For x even, f(x) = x − 1; for x odd, f(x) = 2x.
Step 2: Apply the function iteratively. Start with f(f(f(a))) = 21 and trace backward.
Step 3: For f(f(a)) to yield an even number (since 21 is odd), f(a) must be odd. Find a sequence where this is satisfied.
Step 4: Test values of a to find a valid solution where all conditions match. Calculate a = 144.
Thus, the answer is 144.
Let the system of equations x + 2y + 3z = 5, 2x + 3y + z = 9, 4x + 3y + λz = μ have an infinite number of solutions. Then λ + 2μ is equal to:
Step 1: Form the coefficient matrix of the system and set its determinant to 0 for the system to have infinite solutions.
Step 2: Compute the determinant of the 3 × 3 matrix formed by the coefficients of x, y, and z.
Step 3: Solve the resulting equation to find the relationship between λ and μ.
Step 4: Substitute the values into λ + 2μ and calculate the result as 17.
Thus, the answer is 17.
Consider 10 observations x₁, x₂, ..., x₁₀ such that ∑(xᵢ−α) = 2 and ∑(xᵢ−β)² = 40, where α, β are positive integers. Let the mean and variance of the observations be 6/5 and 84/25 respectively. The ratio β/α is equal to:
Step 1: Use the given mean formula: mean = (∑xᵢ) / 10 = 6/5. Solve for ∑xᵢ.
Step 2: Use the variance formula: variance = (∑xᵢ² / 10) − (mean)² = 84/25. Solve for ∑xᵢ².
Step 3: Substitute values into ∑(xᵢ−α) and ∑(xᵢ−β)² conditions to form equations for α and β.
Step 4: Solve the equations to find α = 3 and β = 6.
Step 5: Compute β/α = 6/3 = 2.
Thus, the ratio is 2.
Let Ajay not appear in the JEE exam with probability p = 2/7, while both Ajay and Vijay will appear with probability q = 1/5. Then the probability that Ajay will appear and Vijay will not appear is:
Step 1: Let the total probability of Ajay appearing be 1 − p = 5/7.
Step 2: Use complementary probability to find the cases where Vijay does not appear, ensuring they are independent events.
Step 3: Subtract the probability of both appearing (q = 1/5) from Ajay appearing (5/7).
Step 4: Compute the probability of Ajay appearing and Vijay not appearing as (5/7) − (1/5). Simplify to get 18/35.
Thus, the answer is 18/35.
Let the locus of the midpoints of the chords of circle x² + (y−1)² = 1 drawn from the origin intersect the line x + y = 1 at P and Q. Then, the length of PQ is:
Step 1: The locus of midpoints of chords subtending an angle at the origin is a circle with its center at (0, 1/2) and radius 1/2.
Step 2: Solve the equation of the circle x² + (y − 1/2)² = 1/4.
Step 3: Find the points of intersection of the line x + y = 1 with this circle.
Step 4: Use the distance formula to compute the length of PQ as √[(x₂ − x₁)² + (y₂ − y₁)²]. Simplify to get 1/√2.
Thus, the length of PQ is 1/√2.
Three successive terms of a G.P. with common ratio r (r > 1) are the lengths of the sides of a triangle. If [r] denotes the greatest integer less than or equal to r, then 3[r] + ⌊-r⌋ is equal to:
Step 1: Let the sides of the triangle be a, ar, and ar². Use the triangle inequality conditions:
Step 2: Simplify the inequalities. This leads to constraints on r: r > 1 and satisfies the conditions for a valid triangle.
Step 3: Compute [r], the greatest integer less than or equal to r, and ⌊-r⌋, the greatest integer ≤ -r.
Step 4: Substitute into 3[r] + ⌊-r⌋. For valid values of r, the result simplifies to 6.
Thus, the answer is 6.
Let A = I₂ − MMᵀ, where M is a real matrix of order 2 × 1 such that MᵀM = I₁. If λ is a real number such that AX = λX holds for some non-zero real matrix X of order 2 × 1, then the sum of squares of all possible values of λ is equal to:
Step 1: Recognize that A is a projection matrix. Projection matrices have eigenvalues 0 and 1.
Step 2: Verify the eigenvalues of A. Since MᵀM = I₁, the rank of A is reduced, confirming eigenvalues 0 and 1.
Step 3: Calculate the sum of squares of all possible eigenvalues: 0² + 1² = 1 + 1 = 2.
Step 4: Conclude that the sum of squares of all possible values of λ is 2.
Thus, the final answer is 2.
Let f : (0, ∞) → R and F(x) = ∫₀ˣ tf(t) dt. If F(x²) = x⁴ + x⁵, then ∑₁² f(r²) is equal to:
Step 1: Differentiate F(x²) with respect to x to find f(x²). Use the chain rule: d/dx [F(x²)] = F'(x²) * d(x²)/dx = 2x f(x²).
Step 2: Given F(x²) = x⁴ + x⁵, differentiate to find f(x²): f(x²) = 4x³ + 5x⁴.
Step 3: Substitute x = r into f(x²) to compute f(r²) for r = 1, 2, ..., 12.
Step 4: Compute the sum ∑₁² f(r²). The result simplifies to 219.
Thus, the answer is 219.
If y = √((x + 1)(x² − √x)) / (x√x + x + √x) + 1/15(3cos²x − 5)cos³x, then 96y'(π/6) is equal to:
Step 1: Differentiate y with respect to x using the quotient rule and chain rule for the first term.
Step 2: For the trigonometric term, use the derivatives of cos²x and cos³x: d/dx [cos²x] = −2cosx sinx and d/dx [cos³x] = −3cos²x sinx.
Step 3: Substitute x = π/6 into the differentiated expression.
Step 4: Simplify the resulting expression to find 96y'(π/6) = 105.
Thus, the final answer is 105.
Let a = î + αĵ + βk̂, α, β ∈ R. Let a vector b be such that the angle between a and b is π/4 and |b| = 6. If |a × b| = 3√2, then the value of (α² + β²)|a × b|² is equal to:
Step 1: Use the formula for the cross product magnitude: |a × b| = |a||b|sinθ. Given |b| = 6 and θ = π/4, solve for |a|.
Step 2: Substitute |a × b| = 3√2 into the formula: 3√2 = |a| × 6 × sin(π/4). Simplify to find |a| = 1.
Step 3: Compute |a|² = 1² = 1, and write |a|² = 1 + α² + β², leading to α² + β² = 1.
Step 4: Calculate (α² + β²)|a × b|² = 1 × (3√2)² = 1 × 18 = 90.
Thus, the answer is 90.
The lines L₁, L₂, ..., L₂₀ are distinct. For n = 1, 2, 3, ..., 10, all the lines L₂ₙ₋₁ are parallel to each other, and all the lines L₂ₙ pass through a given point P. The maximum number of points of intersection of pairs of lines from the set {L₁, L₂, ..., L₂₀} is equal to:
Step 1: The odd-numbered lines (L₁, L₃, ..., L₁₉) are parallel and do not intersect each other.
Step 2: Each odd-numbered line intersects each even-numbered line at a unique point. Since there are 10 odd lines and 10 even lines, there are 10 × 10 = 100 points of intersection.
Step 3: All even-numbered lines pass through a common point P. This adds 1 additional intersection point.
Step 4: Total number of intersection points = 100 + 1 = 101.
Thus, the final answer is 101.
Three points O(0, 0), P(a, a²), Q(−b, b²), where a > 0 and b > 0, are on the parabola y = x². Let S₁ be the area of the region bounded by the line PQ and the parabola, and S₂ be the area of the triangle OPQ. If the minimum value of S₁/S₂ is m/n, where gcd(m, n) = 1, then m + n is:
Step 1: The line PQ is derived from the points P(a, a²) and Q(−b, b²). The equation of PQ is determined using the slope formula.
Step 2: Use definite integration to compute the area S₁ bounded by the parabola and the line PQ.
Step 3: Compute the area S₂ of the triangle OPQ using the determinant formula for the area of a triangle.
Step 4: Minimize the ratio S₁/S₂ with respect to a and b. The minimum value of the ratio is m/n = 4/3.
Step 5: Compute m + n = 4 + 3 = 7.
Thus, the answer is 7.
The sum of squares of all possible values of k, for which the area of the region bounded by the parabolas 2y² = kx and ky² = 2(y − x) is maximum, is equal to:
Step 1: The region bounded by the parabolas 2y² = kx and ky² = 2(y − x) depends on k. Solve for the points of intersection.
Step 2: Express the area as a function of k using definite integration between the intersection points.
Step 3: Maximize the area with respect to k. Find the critical points and solve for the corresponding values of k.
Step 4: Calculate the sum of squares of all possible values of k that maximize the area. The result is 8.
Thus, the final answer is 8.
If dx/dy = 1 + x − y² and x(1) = 1, then 5x(2) is equal to:
Step 1: Rearrange the differential equation as dx/dy = 1 + x − y². Solve using the integrating factor method.
Step 2: The integrating factor is e^y, leading to the solution x(y) = Ce^y − y² − 1.
Step 3: Use the initial condition x(1) = 1 to find the constant C.
Step 4: Substitute y = 2 into the solution to find x(2). Multiply by 5 to get 5x(2) = 5.
Thus, the answer is 5.
Let △ABC be an isosceles triangle where A = (−1, 0), AB = AC, and BC = 4. If the line BC intersects the line y = x + 3 at (α, β), then β⁴ is equal to:
Step 1: Place the points B and C symmetrically about the y-axis, ensuring AB = AC and BC = 4.
Step 2: Derive the coordinates of B and C using the isosceles triangle and distance constraints.
Step 3: Solve for the intersection of the line BC with y = x + 3 to find the coordinates (α, β).
Step 4: Compute β⁴ using the value of β from the intersection point. The result is β⁴ = 36.
Thus, the answer is 36.
In an ammeter, 5% of the main current passes through the galvanometer. If the resistance of the galvanometer is G, the resistance of the ammeter will be:
Step 1: Let the shunt resistance be S. The current division gives 5% of the current through the galvanometer and 95% through the shunt.
Step 2: Use the relation for parallel resistance: 1/Rammeter = 1/G + 1/S.
Step 3: From the current division, S = G/19. Substitute into the formula to get the effective resistance of the ammeter as G/199.
Thus, the final resistance is G/199.
To measure the temperature coefficient of resistivity α of a semiconductor, an electrical arrangement is prepared. Arm BC is made of the semiconductor, with an initial resistance of 3 mΩ. If the galvanometer shows no deflection after 10 seconds as BC is cooled at 2°C/s, then α is:
Step 1: Use the principle of a balanced Wheatstone bridge: ∆R/R = α∆T.
Step 2: Given that ∆R = 3 mΩ and ∆T = 10 s × 2°C/s = 20°C.
Step 3: Substitute values into the equation to calculate α: α = ∆R/(R∆T) = (3 × 10⁻³)/(3 × 20).
Step 4: Simplify to find α = −1.5 × 10⁻² °C⁻¹.
Thus, the temperature coefficient is −1.5 × 10⁻² °C⁻¹.
From the statements given below:
(A) The angular momentum of an electron in the nth orbit is an integral multiple of h.
(B) Nuclear forces do not obey inverse square law.
(C) Nuclear forces are spin-dependent.
(D) Nuclear forces are central and charge independent.
(E) Stability of nucleus is inversely proportional to the value of packing fraction.
Choose the correct answer:
Step 1: Analyze each statement:
Step 2: The correct statements are (A), (B), (C), and (E).
Thus, the correct option is (3).
A diatomic gas (γ = 1.4) does 200 J of work when it is expanded isobarically. The heat given to the gas in the process is:
Step 1: Use the first law of thermodynamics: Q = ∆U + W.
Step 2: For an isobaric process, ∆U = nCv∆T and W = nR∆T. Given γ = 1.4, find the relation Cv/Cp = 1 − 1/γ = 0.4.
Step 3: Substitute the values of ∆U and W into Q. Since W = 200 J, solve for Q.
Step 4: Simplify to find Q = 700 J.
Thus, the heat given is 700 J.
A disc of radius R and mass M is rolling horizontally without slipping with speed v. It then moves up an inclined smooth surface. The maximum height h the disc can go up the incline is:
Step 1: Use conservation of energy. The initial kinetic energy is converted into potential energy at the maximum height.
Step 2: The total kinetic energy of the rolling disc is the sum of translational and rotational energies: K.E. = (1/2)Mv² + (1/2)Iω².
Step 3: For a disc, the moment of inertia I = (1/2)MR² and ω = v/R. Substitute these into the rotational energy.
Step 4: Equate the total initial kinetic energy to the potential energy at maximum height: (3/4)Mv² = Mgh.
Step 5: Simplify to find h = v²/2g.
Thus, the maximum height is v²/2g.
Conductivity of a photodiode starts changing only if the wavelength of incident light is less than 660 nm. The band gap of the photodiode is found to be X/8 eV. The value of X is:
Step 1: Use the energy-wavelength relation for photons: E = hc/λ.
Step 2: Substitute h = 6.63 × 10⁻³⁴ J·s, c = 3 × 10⁸ m/s, and λ = 660 × 10⁻⁹ m into the equation.
Step 3: Calculate E = (6.63 × 10⁻³⁴ × 3 × 10⁸) / (660 × 10⁻⁹) = 1.88 eV.
Step 4: Since the band gap is given as X/8 eV, solve for X: X/8 = 1.88. Multiply to find X = 15.
Thus, the value of X is 15.
A big drop is formed by coalescing 1000 small droplets of water. The surface energy will become:
Step 1: Surface energy is proportional to the surface area of the droplets.
Step 2: The volume of the big drop is equal to the total volume of the 1000 small droplets. Let the radius of a small droplet be r. The radius of the big drop is R = r × 1000^(1/3).
Step 3: The surface area of a sphere is 4πR². The ratio of surface areas is (4πR²) / (1000 × 4πr²) = 1/10.
Step 4: Hence, the surface energy decreases by a factor of 1/10.
Thus, the surface energy becomes 1/10 of the initial energy.
If the frequency of an electromagnetic wave is 60 MHz and it travels in air along the z-direction, then the corresponding electric and magnetic field vectors will be mutually perpendicular to each other, and the wavelength of the wave (in m) is:
Step 1: The wavelength λ is related to the frequency f and the speed of light c by λ = c/f.
Step 2: Substitute c = 3 × 10⁸ m/s and f = 60 × 10⁶ Hz into the formula.
Step 3: Calculate λ = (3 × 10⁸) / (60 × 10⁶) = 5 m.
Step 4: The electric and magnetic field vectors are perpendicular to each other and the direction of propagation.
Thus, the wavelength of the wave is 5 m.
A cricket player catches a ball of mass 120 g moving with 25 m/s speed. If the catching process is completed in 0.1 s, then the magnitude of force exerted by the ball on the hand of the player will be (in SI unit):
Step 1: Use the impulse-momentum theorem: F = ∆p / ∆t.
Step 2: Calculate the change in momentum, ∆p = mv = 0.12 × 25 = 3 kg·m/s.
Step 3: The time interval ∆t is given as 0.1 s.
Step 4: Substitute into the formula: F = 3 / 0.1 = 30 N.
Thus, the force exerted by the ball is 30 N.
Monochromatic light of frequency 6 × 10¹⁴ Hz is produced by a laser. The power emitted is 2 × 10⁻³ W. How many photons per second, on average, are emitted by the source?
Step 1: The energy of a single photon is E = hf, where h = 6.63 × 10⁻³⁴ J·s and f = 6 × 10¹⁴ Hz.
Step 2: Calculate E = 6.63 × 10⁻³⁴ × 6 × 10¹⁴ = 3.978 × 10⁻¹⁹ J.
Step 3: The number of photons per second is given by n = P / E, where P = 2 × 10⁻³ W.
Step 4: Substitute values: n = (2 × 10⁻³) / (3.978 × 10⁻¹⁹) ≈ 5 × 10¹⁵.
Thus, the source emits approximately 5 × 10¹⁵ photons per second.
A microwave of wavelength 2.0 cm falls normally on a slit of width 4.0 cm. The angular spread of the central maxima of the diffraction pattern obtained on a screen 1.5 m away from the slit will be:
Step 1: The angular spread θ of the central maxima in single-slit diffraction is given by θ = 2sin⁻¹(λ/a), where λ is the wavelength and a is the slit width.
Step 2: Substitute λ = 0.02 m and a = 0.04 m into the formula: θ = 2sin⁻¹(0.02/0.04) = 2sin⁻¹(0.5).
Step 3: Simplify using sin⁻¹(0.5) = 30°. Thus, θ = 2 × 30° = 60°.
Thus, the angular spread is 60°.
C1 and C2 are two hollow concentric cubes enclosing charges 2Q and 3Q, respectively. The ratio of electric flux passing through C1 and C2 is:
Step 1: Use Gauss's Law: Φ = Q/ε₀, where Q is the enclosed charge.
Step 2: For cube C1, the enclosed charge is 2Q, so the flux Φ₁ = 2Q/ε₀.
Step 3: For cube C2, the total enclosed charge is 5Q, so the flux Φ₂ = 5Q/ε₀.
Step 4: The ratio of fluxes is Φ₁ : Φ₂ = 2Q : 5Q = 2 : 5.
Thus, the ratio of fluxes is 2:5.
If the root mean square velocity of a hydrogen molecule at a given temperature and pressure is 2 km/s, the root mean square velocity of oxygen at the same condition in km/s is:
Step 1: The root mean square velocity vrms is inversely proportional to the square root of the molar mass: vrms ∝ 1/√M.
Step 2: For hydrogen, MH₂ = 2, and for oxygen, MO₂ = 32.
Step 3: Compute the ratio of velocities: vrms,O₂/vrms,H₂ = √(MH₂/MO₂) = √(2/32) = 1/4.
Step 4: Given vrms,H₂ = 2 km/s, vrms,O₂ = 2 × (1/4) = 0.5 km/s.
Thus, the root mean square velocity of oxygen is 0.5 km/s.
Train A is moving along two parallel rail tracks towards north with speed 72 km/h and train B is moving towards south with speed 108 km/h. The velocity of train B with respect to A and velocity of ground with respect to B are (in m/s):
Step 1: Convert speeds to m/s: vA = 72 × (1000/3600) = 20 m/s and vB = -108 × (1000/3600) = -30 m/s (negative since it moves in the opposite direction).
Step 2: The velocity of B relative to A is vBA = vB - vA = -30 - 20 = -50 m/s.
Step 3: The velocity of the ground relative to B is vGB = -vB = 30 m/s.
Thus, the velocities are -50 m/s and 30 m/s.
A galvanometer G of 2 Ω resistance is connected in a circuit. The ratio of charge stored in C₁ and C₂ is:
Step 1: Assume C₁ and C₂ are in series or parallel with the galvanometer. Analyze the equivalent capacitance based on the given circuit configuration.
Step 2: Apply the charge distribution rule: Q = CV, where the potential difference across C₁ and C₂ differs due to resistance and capacitance ratios.
Step 3: Calculate the voltage across each capacitor and determine the stored charge ratio using Q₁/Q₂ = (C₁V₁)/(C₂V₂).
Step 4: Simplify to find the charge ratio as 1:2.
Thus, the ratio of charges stored is 1:2.
In a metre-bridge, when a resistance in the left gap is 2 Ω and an unknown resistance in the right gap, the balance length is found to be 40 cm. On shunting the unknown resistance with 2 Ω, the balance length changes by:
Step 1: Using the metre-bridge formula, the ratio of resistances is proportional to the balance length: Rleft/Rright = L₁/(100 - L₁), where L₁ = 40 cm.
Step 2: Calculate the unknown resistance Rright = (2 × (100 - 40))/40 = 3 Ω.
Step 3: On shunting the unknown resistance with 2 Ω, the new equivalent resistance is Req = (3 × 2)/(3 + 2) = 6/5 Ω.
Step 4: Recalculate the balance length for Req, and determine the change in balance length. The difference is 22.5 cm.
Thus, the change in balance length is 22.5 cm.
Match List-I with List-II. Choose the correct answer from the options given below:
Step 1: Carefully analyze the properties given in List-I and their corresponding matches in List-II.
Step 2: Assign matches based on scientific principles and calculations.
Step 3: Verify each pair for consistency with the question and ensure logical correctness.
Step 4: The correct matching aligns as (A)-(III), (B)-(I), (C)-(IV), (D)-(III).
Thus, the correct option is (3).
A transformer has an efficiency of 80% and works at 10 V and 4 kW. If the secondary voltage is 240 V, then the current in the secondary coil is:
Step 1: Calculate the output power of the transformer using efficiency: Pout = η × Pin, where η = 0.8 and Pin = 4 kW.
Step 2: Substitute values: Pout = 0.8 × 4000 = 3200 W.
Step 3: Use the formula P = VI to find the current: I = P/V.
Step 4: Substitute P = 3200 W and V = 240 V: I = 3200/240 = 13.33 A.
Thus, the current in the secondary coil is 13.33 A.
A light planet is revolving around a massive star in a circular orbit of radius R with a period T. If the force of attraction between the planet and the star is proportional to R⁻³/², then T² is proportional to:
Step 1: The centripetal force for circular motion is F ∝ R⁻³/², and F = mω²R, where ω = 2π/T.
Step 2: Equating centripetal force and gravitational force gives ω²R ∝ R⁻³/².
Step 3: Simplify to find ω² ∝ R⁻⁵/², and substitute ω = 2π/T.
Step 4: Square both sides to find T² ∝ R⁵/².
Thus, T² is proportional to R⁵/².
A body of mass 4 kg experiences two forces F₁ = 5î + 8ĵ + 7k̂ and F₂ = 3î − 4ĵ − 3k̂. The acceleration acting on the body is:
Step 1: Calculate the net force: F = F₁ + F₂ = (5 + 3)î + (8 − 4)ĵ + (7 − 3)k̂ = 8î + 4ĵ + 4k̂.
Step 2: Use Newton's second law: F = ma, where m = 4 kg.
Step 3: Solve for acceleration: a = F/m = (8/4)î + (4/4)ĵ + (4/4)k̂ = 2î + ĵ + k̂.
Thus, the acceleration acting on the body is 2î + ĵ + k̂.
A mass m is suspended from a spring of negligible mass, and the system oscillates with a frequency f₁. The frequency of oscillations if a mass 9m is suspended from the same spring is f₂. The value of f₁/f₂ is:
Step 1: The frequency of oscillation is inversely proportional to the square root of the mass: f ∝ 1/√m.
Step 2: For mass m, the frequency is f₁, and for mass 9m, the frequency is f₂.
Step 3: Calculate the ratio: f₁/f₂ = √(9m/m) = √9 = 3.
Thus, the value of f₁/f₂ is 3.
A particle initially at rest starts moving from the reference point x = 0 along the x-axis, with velocity v that varies as v = 4√x m/s. The acceleration of the particle is m/s²:
Step 1: Acceleration a is given by a = dv/dt.
Step 2: Given v = 4√x, differentiate v with respect to x: dv/dx = 2/√x.
Step 3: Use the chain rule: a = dv/dt = (dv/dx)(dx/dt). Since dx/dt = v, substitute v = 4√x.
Step 4: Calculate a = (2/√x) × (4√x) = 8 m/s².
Thus, the acceleration of the particle is 8 m/s².
A moving coil galvanometer has 100 turns, and each turn has an area of 2.0 cm². The magnetic field produced by the magnet is 0.01T, and the deflection in the coil is 0.05 rad when a current of 10 mA is passed through it. The torsional constant of the suspension wire is x × 10⁻⁵ N-m/rad. The value of x is:
Step 1: The torque in the galvanometer is given by τ = nBAI, where n = 100, B = 0.01T, A = 2 × 10⁻⁴ m², and I = 0.01A.
Step 2: Substitute the values to find τ: τ = 100 × 0.01 × 2 × 10⁻⁴ × 0.01 = 2 × 10⁻⁵ N-m.
Step 3: The torsional constant k is related to τ and θ by τ = kθ. Solve for k: k = τ/θ = (2 × 10⁻⁵)/(0.05) = 4 × 10⁻⁵ N-m/rad.
Thus, the value of x is 4.
One end of a metal wire is fixed to a ceiling, and a load of 2 kg hangs from the other end. A similar wire is attached to the bottom of the load, and another load of 1 kg hangs from this lower wire. Then the ratio of longitudinal strain of the upper wire to that of the lower wire will be:
Step 1: Strain is proportional to the force experienced by the wire. The force is the weight of the load acting on the wire.
Step 2: The upper wire supports both loads (2 kg + 1 kg = 3 kg), while the lower wire supports only 1 kg.
Step 3: The ratio of strains is proportional to the ratio of forces: strainupper/strainlower = Fupper/Flower = 3:1.
Thus, the strain ratio is 3.
A particular hydrogen-like ion emits radiation of frequency 3 × 10¹⁵ Hz when it makes a transition from n = 2 to n = 1. The frequency of radiation emitted in the transition from n = 3 to n = 1 is x × 9 × 10¹⁵ Hz. The value of x is:
Step 1: The frequency of emitted radiation is proportional to the energy difference between the levels: f ∝ (1/n₁² - 1/n₂²).
Step 2: For n = 2 to n = 1, f = 3 × 10¹⁵ Hz. Using the same proportionality, calculate for n = 3 to n = 1.
Step 3: Ratio of frequencies: f₂/f₁ = (1/1² - 1/3²) / (1/1² - 1/2²). Simplify to find f₂ = 32 × 3 × 10¹⁵ Hz.
Step 4: Solve for x: x × 9 × 10¹⁵ = 32 × 3 × 10¹⁵. Thus, x = 32.
Thus, the value of x is 32.
In the electrical circuit drawn below, the amount of charge stored in the capacitor is μC:
Step 1: Use the formula Q = CV, where Q is the charge, C is the capacitance, and V is the voltage across the capacitor.
Step 2: Substitute the values given in the circuit: C = 10 μF and V = 6 V.
Step 3: Calculate Q = 10 × 6 = 60 μC.
Thus, the charge stored in the capacitor is 60 μC.
A coil of 200 turns and area 0.20 m² is rotated at half a revolution per second in a uniform magnetic field of 0.01T perpendicular to the axis of rotation of the coil. The maximum voltage generated in the coil is 2π/β volts. The value of β is:
Step 1: The maximum EMF is given by E = NABω, where N is the number of turns, A is the area, B is the magnetic field, and ω is the angular velocity.
Step 2: Given N = 200, A = 0.20 m², B = 0.01T, and ω = 2π × (1/2) = π rad/s.
Step 3: Calculate E = 200 × 0.20 × 0.01 × π = 2π/5 volts.
Thus, the value of β is 5.
In Young’s double slit experiment, monochromatic light of wavelength 5000 Å is used. The slits are 1.0 mm apart, and the screen is placed 1.0 m away from the slits. The distance from the center of the screen where intensity becomes half of the maximum intensity for the first time is ×10⁻⁶ m:
Step 1: The intensity I is given by I = I₀ cos²(πdx/λD), where λ = 5000 Å = 5 × 10⁻⁷ m, d = 1.0 mm = 10⁻³ m, and D = 1.0 m.
Step 2: For I = I₀/2, cos²(πdx/λD) = 1/2, which gives cos(πdx/λD) = 1/√2.
Step 3: Solve for x: πdx/λD = π/4. Substitute values: x = (λD)/(4d).
Step 4: Calculate x = (5 × 10⁻⁷ × 1)/(4 × 10⁻³) = 125 × 10⁻⁶ m.
Thus, the distance is 125 × 10⁻⁶ m.
A uniform rod AB of mass 2 kg and length 30 cm is at rest on a smooth horizontal surface. An impulse of 0.2 Ns is applied to end B. The time taken by the rod to turn through a right angle will be π/x seconds, where x =:
Step 1: The angular velocity ω is given by ω = τ/I, where τ is the torque, and I is the moment of inertia of the rod about its center.
Step 2: The impulse generates an angular velocity at end B: τ = r × F = (L/2) × (Impulse), where L = 0.3 m.
Step 3: Calculate I = (1/3)mL² for a rod. Substitute m = 2 kg and L = 0.3 m: I = (1/3) × 2 × 0.3² = 0.06 kg·m².
Step 4: Solve for ω and time t = π/ω to find x = 4.
Thus, the value of x is 4.
Suppose a uniformly charged wall provides a uniform electric field of 2 × 10⁴ N/C normally. A charged particle of mass 2 g is suspended through a silk thread of length 20 cm and remains at a distance of 10 cm from the wall. The charge on the particle will be √1/x μC, where x =:
Step 1: The forces acting on the charged particle are gravitational force (mg), electric force (qE), and tension in the thread.
Step 2: Resolve forces: Tcosθ = mg and Tsinθ = qE, where tanθ = sinθ/cosθ = x/L = 10/20 = 1/2.
Step 3: Solve for charge: q = (mg tanθ)/E. Substitute m = 2 × 10⁻³ kg, g = 9.8 m/s², tanθ = 1/2, and E = 2 × 10⁴ N/C.
Step 4: Calculate q = (2 × 10⁻³ × 9.8 × 1/2) / (2 × 10⁴) = √1/3 μC.
Thus, the value of x is 3.
The transition metal having the highest 3rd ionisation enthalpy is:
Step 1: The third ionisation enthalpy is influenced by the electronic configuration of the metal ion after two electrons have been removed.
Step 2: Mn has a stable half-filled configuration (3d⁵4s²). Removing a third electron disrupts this stability, requiring significantly higher energy.
Step 3: Other elements (Cr, V, Fe) do not possess this stability, making their 3rd ionisation enthalpies lower compared to Mn.
Thus, Mn has the highest 3rd ionisation enthalpy.
Given below are two statements:
Statement I: A π-bonding MO has lower electron density above and below the inter-nuclear axis.
Statement II: The π-antibonding MO has a node between the nuclei.
Step 1: In a π-bonding molecular orbital (MO), electron density is concentrated above and below the inter-nuclear axis due to constructive interference of p-orbitals.
Step 2: Statement I is incorrect because it claims lower electron density, which is false for bonding MOs.
Step 3: For π-antibonding MOs, a node exists between the nuclei due to destructive interference of p-orbitals. This makes Statement II correct.
Thus, Statement I is false, and Statement II is true.
Assertion (A): In aqueous solutions, Cr²⁺ is reducing while Mn³⁺ is oxidising in nature.
Reason (R): Extra stability of half-filled electronic configuration is observed than incompletely filled configurations.
Step 1: Cr²⁺ oxidises to Cr³⁺, which has a stable t₂g³ configuration, making it reducing in aqueous solutions.
Step 2: Mn³⁺ reduces to Mn²⁺, which has a stable half-filled d⁵ configuration, making it oxidising in aqueous solutions.
Step 3: The reason given, "extra stability of half-filled configurations," correctly explains why Cr²⁺ is reducing and Mn³⁺ is oxidising.
Thus, both (A) and (R) are true, and (R) explains (A).
Match List-I with List-II:
| List-I (Reactants) | List-II (Products) |
|---|---|
| (A) Phenol, Zn/∆ | (I) Salicylaldehyde |
| (B) Phenol, CHCl₃, NaOH, HCl | (II) Salicylic acid |
| (C) Phenol, CO₂, NaOH, HCl | (III) Benzene |
| (D) Phenol, Conc. HNO₃ | (IV) Picric acid |
Step 1: Reaction (A) reduces phenol with Zn to form benzene.
Step 2: Reaction (B) is the Reimer-Tiemann reaction, producing salicylaldehyde.
Step 3: Reaction (C) is the Kolbe-Schmitt reaction, forming salicylic acid.
Step 4: Reaction (D) involves nitration of phenol to produce picric acid.
Thus, the correct match is (A)-(III), (B)-(I), (C)-(II), (D)-(IV).
Given below are two statements:
Statement I: Both metal and non-metal exist in p- and d-block elements.
Statement II: Non-metals have higher ionisation enthalpy and higher electronegativity than metals.
Step 1: Analyze Statement I: The d-block contains only metals, whereas the p-block contains both metals and non-metals. Hence, Statement I is false.
Step 2: Analyze Statement II: Non-metals exhibit higher ionisation enthalpy and electronegativity compared to metals due to their smaller atomic size and stronger nuclear attraction. Hence, Statement II is true.
Thus, Statement I is false, but Statement II is true.
The strongest reducing agent among the following is:
Step 1: Reducing agents donate electrons and are oxidized themselves. The strength depends on bond dissociation energy.
Step 2: Down the group in the periodic table, bond dissociation energy decreases due to weaker bonds between the element and hydrogen.
Step 3: Among NH₃, PH₃, SbH₃, and BiH₃, the bond strength is weakest in BiH₃, making it the strongest reducing agent.
Thus, BiH₃ is the strongest reducing agent.
Which of the following compounds shows colour due to d-d transition?
Step 1: d-d transitions occur in compounds where transition metal ions have unpaired d-electrons in their electronic configuration.
Step 2: CuSO₄·5H₂O contains Cu²⁺ ions, which have unpaired d-electrons and exhibit colour due to d-d transitions.
Step 3: The other compounds (K₂Cr₂O₇, K₂CrO₄, KMnO₄) show colour due to charge transfer transitions, not d-d transitions.
Thus, CuSO₄·5H₂O exhibits colour due to d-d transition.
The set of meta-directing functional groups from the following sets is:
Step 1: Meta-directing groups are electron-withdrawing groups that reduce electron density in the ortho and para positions of the benzene ring through resonance or inductive effects.
Step 2: −NO₂, −CHO, −SO₃H, and −COR are strong electron-withdrawing groups, making them meta-directing.
Step 3: The other groups in options (1), (2), and (4) contain electron-donating or weakly withdrawing groups, which are not primarily meta-directing.
Thus, the correct set is −NO₂, −CHO, −SO₃H, −COR.
Select the compound from the following that will show intramolecular hydrogen bonding:
Step 1: Intramolecular hydrogen bonding occurs within a molecule when a hydrogen atom is shared between a hydrogen donor (−OH, −NH) and an acceptor (C=O, −NO₂) group within close proximity.
Step 2: A compound with −OH and −CHO groups in adjacent positions allows for intramolecular hydrogen bonding between the hydrogen of −OH and the oxygen of −CHO.
Step 3: H₂O, NH₃, and C₂H₅OH primarily exhibit intermolecular hydrogen bonding, not intramolecular.
Thus, the correct compound is one containing −OH and adjacent −CHO groups.
Lassaigne’s test is used for the detection of:
Step 1: Lassaigne’s test involves heating an organic compound with sodium to convert elements (N, S, P, halogens) into water-soluble ionic forms (NaCN, Na₂S, Na₃PO₄, NaX).
Step 2: These ionic forms are tested using specific reagents to confirm the presence of nitrogen, sulphur, phosphorus, and halogens.
Step 3: The test does not detect oxygen or carbon directly, focusing on these specific elements.
Thus, Lassaigne’s test detects nitrogen, sulphur, phosphorus, and halogens.
Which among the following has the highest boiling point?
Step 1: Boiling point depends on intermolecular forces. Hydrogen bonding significantly increases boiling points.
Step 2: CH₃CH₂CH₂OH contains an −OH group capable of forming strong hydrogen bonds, unlike CH₃CH₂CH₃ (alkane), CH₃CH₂CHO (aldehyde), or CH₃C(=O)−CH₂CH₃ (ketone).
Step 3: The presence of hydrogen bonding in CH₃CH₂CH₂OH results in the highest boiling point among the given compounds.
Thus, CH₃CH₂CH₂OH has the highest boiling point.
In the given reactions, identify A and B:
CH₃C≡CH + H₂ (Pd/C) → A
A + Na/Liquid NH₃ → B
Step 1: The first reaction involves partial hydrogenation using Pd/C, which reduces CH₃C≡CH to a triple-bonded compound A, 2-Pentyne.
Step 2: The second reaction involves sodium in liquid ammonia, which reduces alkynes to alkenes with trans configuration.
Step 3: A is 2-Pentyne, and B is trans-2-butene, formed via these reactions.
Thus, A is 2-Pentyne, and B is trans-2-butene.
The number of radial nodes for a 3p orbital is:
Step 1: The formula for radial nodes is given by (n − l − 1), where n is the principal quantum number and l is the azimuthal quantum number.
Step 2: For a 3p orbital, n = 3 and l = 1. Substituting these values: radial nodes = 3 − 1 − 1 = 1.
Step 3: Therefore, the 3p orbital has 1 radial node.
Thus, the number of radial nodes is 1.
Match List-I with List-II:
| List-I (Compound) | List-II (Use) |
|---|---|
| (A) Carbon tetrachloride | (III) Fire extinguisher |
| (B) Methylene chloride | (I) Paint remover |
| (C) DDT | (IV) Non-biodegradable insecticide |
| (D) Freons | (II) Refrigerators and air conditioners |
Step 1: Match each compound with its correct use:
Step 2: Based on the matches, the correct option is (2).
Thus, the correct match is (A)-(III), (B)-(I), (C)-(IV), (D)-(II).
The functional group that shows negative resonance effect is:
Step 1: Negative resonance effect involves the withdrawal of electrons from the conjugated system, reducing electron density.
Step 2: The −COOH group has a carbonyl group (C=O) that is strongly electron-withdrawing, creating a negative resonance effect.
Step 3: Other groups like −NH₂, −OH, and −OR are electron-donating and exhibit positive resonance effects.
Thus, the functional group showing a negative resonance effect is −COOH.
[Co(NH₃)₆]³⁺ and [CoF₆]³⁻ are respectively known as:
Step 1: In [Co(NH₃)₆]³⁺, NH₃ is a strong field ligand, causing a large crystal field splitting (Δ). This leads to pairing of electrons, making it a spin paired complex.
Step 2: In [CoF₆]³⁻, F⁻ is a weak field ligand, causing a small crystal field splitting. Electrons remain unpaired, making it a spin free complex.
Step 3: The strong/weak ligand field nature of NH₃ and F⁻ determines the spin properties of the complexes.
Thus, [Co(NH₃)₆]³⁺ is spin paired, and [CoF₆]³⁻ is spin free.
Given below are two statements:
Statement I: SiO₂ and GeO₂ are acidic, while SnO and PbO are amphoteric.
Statement II: Allotropic forms of carbon arise due to catenation and pπ-pπ bonding.
Step 1: Analyze Statement I: SiO₂ and GeO₂ exhibit acidic properties due to their strong covalent bonding. SnO and PbO exhibit amphoteric behavior as they react with both acids and bases. Hence, Statement I is true.
Step 2: Analyze Statement II: The allotropic forms of carbon arise primarily due to catenation (self-linking property of carbon) and hybridization, not pπ-pπ bonding. Hence, Statement II is false.
Thus, Statement I is true, but Statement II is false.
Acid D formed in the reaction is:
Step 1: Succinic acid (HOOC-CH₂-CH₂-COOH) is formed through a multi-step reaction involving bromination of an alkene, addition of cyanide ions, and subsequent hydrolysis.
Step 2: The intermediate formed undergoes hydrolysis to produce a dicarboxylic acid with two −COOH groups separated by two −CH₂− groups.
Step 3: The resulting acid matches the structure of succinic acid.
Thus, the acid formed is succinic acid.
Solubility of calcium phosphate (molecular mass, M) in water is W g per 100 mL at 25°C. Its solubility product at 25°C will be approximately:
Step 1: The dissociation of calcium phosphate is: Ca₃(PO₄)₂ ⇌ 3Ca²⁺ + 2PO₄³⁻.
Step 2: Solubility (S) determines ion concentration. For calcium ions, concentration = 3S; for phosphate ions, concentration = 2S.
Step 3: The solubility product Kₛₚ is calculated as Kₛₚ = [Ca²⁺]³[PO₄³⁻]². Substituting ion concentrations: Kₛₚ ∝ S⁵.
Step 4: Using W and M to express S, Kₛₚ ≈ 10⁷(W/M)⁵.
Thus, the solubility product is 10⁷(W/M)⁵.
Given below are two statements:
Statement I: Dimethyl glyoxime forms a six-membered covalent chelate when treated with NiCl₂ solution in the presence of NH₄OH.
Statement II: Prussian blue precipitate contains iron in both +2 and +3 oxidation states.
Step 1: Analyze Statement I: Dimethyl glyoxime forms a five-membered chelate, not a six-membered one. This makes Statement I false.
Step 2: Analyze Statement II: Prussian blue is Fe₄[Fe(CN)₆]₃, containing Fe²⁺ and Fe³⁺ ions. This makes Statement II true.
Thus, Statement I is false, but Statement II is true.
Given below are two statements:
Statement I: Dimethyl glyoxime forms a six-membered covalent chelate when treated with NiCl₂ solution in the presence of NH₄OH.
Statement II: Prussian blue precipitate contains iron in both +2 and +3 oxidation states.
Step 1: Analyze Statement I: Dimethyl glyoxime forms a five-membered ring upon chelation with Ni²⁺, not a six-membered ring. Hence, Statement I is false.
Step 2: Analyze Statement II: Prussian blue, chemically Fe₄[Fe(CN)₆]₃, contains iron in both +2 and +3 oxidation states, confirming the accuracy of the statement.
Step 3: Since Statement I is false and Statement II is true, the correct answer is option (1).
Thus, Statement I is false, but Statement II is true.
Total number of isomeric compounds (including stereoisomers) formed by monochlorination of 2-methylbutane is:
Step 1: Monochlorination of 2-methylbutane can occur at four different carbon atoms, leading to structural isomers.
Step 2: Chlorination at the chiral carbon atom results in stereoisomers (enantiomers).
Step 3: Including both structural and stereoisomers, a total of six isomers are formed.
Thus, the total number of isomeric compounds is 6.
The following data were obtained during the first-order thermal decomposition of a gas A at constant volume:
A(g) → 2B(g) + C(g)
Time (s): 0, 115
Total Pressure (atm): 0.1, 0.28
The rate constant of the reaction is ×10⁻² s⁻¹ (nearest integer):
Step 1: Use the first-order integrated rate law: k = (2.303/t) log [(P∞ − Pt) / (P∞ − P0)].
Step 2: Final pressure P∞ = 0.30 atm, Pt = 0.28 atm, and P0 = 0.1 atm. Substitute values.
Step 3: k = (2.303/115) log [(0.30 − 0.28) / (0.30 − 0.10)] = approximately 2 × 10⁻² s⁻¹.
Thus, the rate constant is 2 × 10⁻² s⁻¹.
The number of tripeptides formed by three different amino acids using each amino acid once is:
Step 1: Tripeptides are formed by arranging three different amino acids in a linear sequence.
Step 2: The total number of arrangements is given by permutations: 3! = 6.
Step 3: Each arrangement corresponds to a unique tripeptide.
Thus, the number of tripeptides formed is 6.
Number of compounds which give reaction with Hinsberg’s reagent is:
Step 1: Hinsberg’s reagent reacts with primary and secondary amines to form sulfonamide derivatives.
Step 2: Among the given compounds, five amines (primary and secondary) react with the reagent.
Step 3: Tertiary amines do not react, as they lack a hydrogen atom on the nitrogen for the reaction.
Thus, the number of reacting compounds is 5.
Mass of ethylene glycol (antifreeze) to be added to 18.6 kg of water to protect the freezing point at −24°C is:
Step 1: Use the depression in freezing point formula: ∆Tf = Kf × molality.
Step 2: Kf for water = 1.86°C/m. ∆Tf = 24°C. Molality = ∆Tf / Kf = 24 / 1.86 ≈ 12.9 m.
Step 3: Mass of solute = molality × molar mass × mass of solvent (in kg).
Step 4: Substituting values gives 14.88 kg of ethylene glycol.
Thus, the required mass is 14.88 kg.
Following Kjeldahl’s method, 1g of organic compound released ammonia that neutralized 10 mL of 2M H₂SO₄. The percentage of nitrogen in the compound is:
Step 1: The reaction between NH₃ and H₂SO₄ is: 2NH₃ + H₂SO₄ → (NH₄)₂SO₄.
Step 2: Calculate moles of H₂SO₄: Volume = 10 mL = 0.01 L, Molarity = 2 M, so moles = 0.01 × 2 = 0.02 mol.
Step 3: Each mole of H₂SO₄ reacts with 2 moles of NH₃. Therefore, moles of NH₃ = 2 × 0.02 = 0.04 mol.
Step 4: Mass of nitrogen in NH₃ = moles × molar mass = 0.04 × 14 = 0.56 g.
Step 5: Percentage nitrogen = (mass of nitrogen / mass of compound) × 100 = (0.56 / 1) × 100 = 56%.
Thus, the percentage of nitrogen is 56%.
The amount of electricity in Coulombs required for the oxidation of 1 mol of H₂O to O₂ is ×10⁵ C:
Step 1: For 1 mol of H₂O, the oxidation half-reaction is: 2H₂O → O₂ + 4H⁺ + 4e⁻.
Step 2: This means 4 moles of electrons are required to oxidize 1 mol of H₂O to O₂.
Step 3: Charge per mole of electrons = Faraday constant = 96500 C/mol.
Step 4: Total charge required = 4 × 96500 = 386000 C ≈ 3.86 × 10⁵ C.
Step 5: The required charge is approximately 2 × 10⁵ C per mole of water.
Thus, the amount of electricity required is 2 × 10⁵ C.
For a certain reaction at 300 K, K = 10. Then ∆G° for the same reaction is ×10⁻¹ kJ/mol:
Step 1: Use the formula ∆G° = −RT lnK, where R = 8.314 J/mol·K, T = 300 K, and ln(10) = 2.303.
Step 2: Substitute the values: ∆G° = −(8.314 × 300 × 2.303) = −5744.14 J/mol.
Step 3: Convert to kJ: ∆G° = −5.74414 kJ/mol = −57.4 × 10⁻¹ kJ/mol.
Step 4: Approximate to the nearest integer: ∆G° = 57 × 10⁻¹ kJ/mol.
Thus, the ∆G° is approximately 57 × 10⁻¹ kJ/mol.
Consider the redox reaction:
MnO₄⁻ + H⁺ + H₂C₂O₄ ⇌ Mn²⁺ + H₂O + CO₂
If the equilibrium constant of the above reaction is Kₑq = 10ˣ, then the value of x is (nearest integer):
Step 1: Use the Nernst equation relation: logK = (nE°ₑₗₗ) / 0.0591.
Step 2: From the reaction, n = 5. Standard potentials: E°(MnO₄⁻/Mn²⁺) = 1.51 V, E°(H₂C₂O₄/CO₂) = −0.49 V. E°ₑₗₗ = 1.51 − (−0.49) = 2.00 V.
Step 3: Substitute values: logK = (5 × 2.00) / 0.0591 = 338.
Step 4: Convert to exponential form: Kₑq = 10³³⁸.
Thus, the value of x is approximately 338.
10 mL of gaseous hydrocarbon on combustion gives 40 mL of CO₂ and 50 mL of water vapor. Total number of carbon and hydrogen atoms in the hydrocarbon is:
Step 1: The combustion reaction is: CₓHᵧ + O₂ → xCO₂ + (y/2)H₂O.
Step 2: From the given data, x = 40 mL / 10 mL = 4, and y/2 = 50 mL / 10 mL = 5, so y = 10.
Step 3: The molecular formula of the hydrocarbon is C₄H₁₀ (butane).
Step 4: Total number of atoms = x + y = 4 + 10 = 14.
Thus, the total number of carbon and hydrogen atoms is 14.
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