
NTA conducted the RE-NEET 2026 Code 50 Exam on June 21 in a single shift from 2:00 PM to 5:15 PM in PBT Mode.
The RE-NEET 2026 Code 50 Exam Question Paper consisted of 3 sections: Physics, Chemistry, and Biology (Botany & Zoology) with 180 Questions carrying a total of 720 Marks, as per the NEET Marking Scheme, +4 Marks for every correct answer, and -1 mark will be deducted for every wrong answer.
RE-NEET 2026 Code 50 Question Paper with Solution PDF is available here for download.
| RE-NEET 2026 Code 50 Question Paper | Download PDF | Check Solutions |
A particle of mass \( M \) moves along the horizontal x-axis from \( x = 0 \) to \( x = L \). The coefficient of kinetic friction varies as \[ \mu_k(x) = \frac{\mu_0}{L} x \] where \( \mu_0 \) and \( L \) are constants. If the total work done by friction during the motion is \[ -\frac{\mu_0 M g L}{n} \] where \( g \) is the acceleration due to gravity, find \( n \).
The mean free path of molecules in an ideal gas A is half that of another ideal gas B. The diameter of the spherical molecules of gas A is twice the diameter of the molecules of gas B. If number densities of the gases A and B are \( n_A \) and \( n_B \), respectively, then the correct option is:
Two identical inductors are connected in two different configurations P and Q, where a time varying current \( I(t) \) is flowing, as shown in the figure. If the induced emf between points a and b for configuration P is \( E_P \) and that for configuration Q is \( E_Q \), then the ratio \( \frac{E_P}{E_Q} \) is:
For sound waves, if the number of nodes for the 5th harmonic of an open-ended pipe is \( n \) and that for the 9th harmonic of the same pipe with one of its ends closed is \( m \), the ratio \( \frac{n}{m} \) is:
Consider a long solenoid of length \( l \) and radius \( r \). If \( n \) is the number of turns per unit length and \( \mu_0 \) is the permeability of free space, the inductance of the solenoid is:
Consider a particle moving along a straight line, whose position as a function of time is given by \[ s(t) = \alpha t^2 - \beta t + \gamma \] where \( \alpha = 1 m s^{-2} \), \( \beta = 6 m s^{-1} \) and \( \gamma = 5 m \). The average speed of the particle, in \( m s^{-1} \), from \( t = 0 \) to \( t = 6 s \) is:
Consider the following nuclear reaction : \[ ^{238}_{92}U \rightarrow ^{234}_{90}Th + ^{4}_{2}He \] Take masses of \( ^{238}U \), \( ^{234}Th \) and \( ^{4}He \) as \( 238.050 u \), \( 234.043 u \) and \( 4.003 u \), respectively. The Q-value for the reaction, in \( keV \), is : (Given : \( 1 u = 931.5 MeV/c^2 \))
A beam of light falls on a metal surface such that photo-electrons are generated. If the power of the light source starts to decrease linearly with time, then the variation of the photocurrent \( I \) and magnitude of the stopping potential \( |V| \) with time is best represented by :
Three identical capacitors P, Q and S, each of capacitance C, are connected to a battery of voltage V, as shown in the figure. If the potential energy stored in the capacitor P and total energy stored in the system are \( U_P \) and \( U_T \), respectively, then the ratio \( \frac{U_P}{U_T} \) is:
Water flows in a streamline motion through a horizontal pipe of circular cross-section as shown in the figure. The pressure difference of water between P and Q is \( 15 N m^{-2} \). The area of cross-section at P and Q are \( 40 cm^2 \) and \( 20 cm^2 \), respectively. The rate of flow of water through the pipe, in \( cm^3 s^{-1} \), is:
A current \( I_0 \) flows through a metallic circular loop of radius \( r \) as shown. The resistance of arc ABC is half that of arc ADC. Find the magnetic field at the centre O.
In the measurement of viscosity of liquids using terminal velocity experiment, spherical balls of same radius but having different densities are used. The variation of the terminal velocity \( v \) with the ratio of density of spherical ball \( (\sigma) \) to density of the liquid \( (\rho) \), is best represented by:
Two planets \( P_1 \) and \( P_2 \) with equal mass have radii \( R_1 \) and \( R_2 \), respectively, where \[ R_2 = \frac{R_1}{2} \] The escape speeds of \( P_1 \) and \( P_2 \) are \( v_1 \) and \( v_2 \), respectively. Then the value of \( \frac{v_2}{v_1} \) is:
In a solar system, the time period of revolution of a planet tracing a circular orbit of radius \( R \) is proportional to:
Two infinitely long parallel conducting wires A and B carry currents \( I \) and \( 2I \), respectively, in the same direction. Wire A lies on an insulated floor while wire B is fixed at a height \( h \) above the floor. The minimum value of \( h \) so that wire A does not rise from the floor is: (where \( \lambda \) is the mass per unit length of wire A)
An ideal Zener diode with breakdown voltage of \( 3 V \) is reverse biased with a negative input voltage \( V_1 = -5 V \). The magnitude of voltage difference between points B and A is:
In an adiabatic expansion, the temperature of one mole of an ideal monoatomic gas \( \left(\gamma = \frac{5}{3}\right) \) decreases from \( 60 K \) to \( 50 K \). The work done by the gas in the process is: (Take the universal gas constant as \( R = 8.3 J mol^{-1}K^{-1} \))
A ray of light with wavelength \( \lambda \) is incident on three different photoelectric cells. The threshold wavelengths are \( \lambda_1 \), \( \lambda_2 \), and \( \lambda_3 \), and the magnitudes of stopping potentials are \( V_1 \), \( V_2 \), and \( V_3 \), respectively. If \[ \lambda_1 \le \lambda, \quad \lambda_2 > \lambda, \quad \lambda_3 \gg \lambda \] the correct option is:
A photon and an electron, each of 20 eV energy, move in free space. The ratio of linear momentum of electron \( p_e \) to that of photon \( p_{ph} \), \( \frac{p_e}{p_{ph}} \), is : (Take \( c = 3 \times 10^8 ms^{-1} \), \( e = 1.6 \times 10^{-19} C \), \( m_e = 9 \times 10^{-31} kg \))
Which of the following measurements require index correction?
A unit positive point charge is taken slowly through an infinitesimally thin tube that is inside a charged dielectric sphere of radius \( R \), having uniform positive charge density \( \rho \), as shown in the figure. The initial and final positions of the charge are marked by A and B, at distances \( 2R \) and \( 3R \) respectively, from the centre O of the sphere. In this process, the magnitude of the total work done on the point charge is \[ \frac{\rho R^2}{n \epsilon_0} \] The value of \( n \) is :
Consider three media P, Q and R with refractive indices \( 1 \), \( 1.25 \) and \( 1.5 \), respectively. The medium Q, having a thickness of \( 5 cm \), is placed between extended media P and R as shown in the figure. An object O is placed at the centre of medium Q. If viewed from medium P near the normal direction, the apparent depth is \( h_1 \). For similar observation from medium R, the apparent depth is \( h_2 \). The value of \( |h_1 - h_2| \) in cm is :
A frictionless circular wire of unit radius is fixed on the horizontal plane. Two point particles of unit mass start moving simultaneously from point A \( \left(\theta = \frac{\pi}{2}\right) \) with identical uniform angular speeds in opposite directions, and meet again at point B \( \left(\theta = -\frac{\pi}{2}\right) \). During this time, which of the following figures schematically represents the magnitude of the total linear momentum \( P \) of the system, as a function of \( \theta \)?
The temperature of a metallic sphere of radius \( R \) is increased by a small thermal expansion \( \Delta T \). If the linear coefficient of thermal expansion of the metal is \( \alpha \), the approximate increase in the volume of the sphere is :
A cylindrical cork of uniform density floats in a liquid of density \( \rho_1 \). If the cork is depressed slightly and released, it oscillates harmonically with time period \( T \). If the same cork floats in another liquid of density \( \rho_2 \), then the similar oscillation has time period \( 2T \). The value of \( \frac{\rho_2}{\rho_1} \) is :
One main scale division of a Vernier calliper is equal to \( 1 mm \) and the number of divisions on the Vernier scale is \( 10 \). When both the jaws touch each other, the Vernier scale shifts to the left of zero of the main scale in such a way that \( 4^{th} \) Vernier division coincides with a division of the main scale. If this Vernier calliper measures the length of a wire to be \( 1 cm \), the actual length of the wire is:
A solid sphere A of radius \( R \) and mass \( M \) is attached to a smaller solid sphere B of radius \( r < R \) and mass \( m < M \). The line joining their centres lies along the horizontal. The moment of inertia of the system calculated about a vertical axis passing through the centre of A is \( I_A \) and that calculated about a vertical axis passing through the centre of B is \( I_B \). The difference \( I_A - I_B \) is :
A spring-mass simple harmonic oscillator has mass \( m \) and spring constant \( k \). If the v–x graph is a circle, then:
A lens combination consists of \( L_1 \) (f = +10 cm) and \( L_2 \) (f = -10 cm) separated by 3 cm. An object is placed 30 cm from \( L_1 \). Find the final image position.
An AC voltage \( V = 220 \sin(2 \times 10^3 t) \) is applied to an LCR circuit (L = 10 mH, C = 25 \(\mu\)F, R = 100 \(\Omega\)). Find current amplitude.
A disc rotates about a fixed axis O. Angular momenta \( L_A \) and \( L_B \) are measured at points A and B where \( OB = 2OA \). Find \( L_A/L_B \).
A loop has area \( A = A_0(1 + \sin t) \). The dissipated power behaves as:
A point charge Q is placed inside a cavity within a solid isolated conducting sphere. Consider points A, B, and C as shown in the figure, where the magnitudes of the electric fields are \( E_A \), \( E_B \), and \( E_C \), respectively. The points B and C are at the same distance from the center of the solid sphere. The correct option is:
A fixed uniformly charged insulating sphere has radius \( R \) and charge \( +Q \). A point charge \( -q \) (\( q \ll Q \)) with mass \( m \) is released from \( 3R \). When the point charge reaches the surface, its speed is:
In the Geiger-Marsden experiment, the number of scattered \(\alpha\)-particles \( N(\theta) \) is plotted against scattering angle \(\theta\). Which plot represents the correct data?
Consider two circuits, (A) and (B), each having two resistors. One of them has a positive temperature coefficient of resistance, \( + \alpha \), while the other one has a negative temperature coefficient of resistance, \( - \alpha \). As the temperature is increased, the correct option that describes the variation of current in these circuits is :
Consider that \(\sigma_s\), \(k_B\), \(b\) represent Stefan-Boltzmann constant, Boltzmann constant and Wien's displacement constant respectively. The dimension of \(\sigma_s k_B^{-1} b\) is :
An electromagnetic wave travelling in a lossless dielectric medium having dielectric constant \( \epsilon_r = 9 \), has electric field \( E_x = E_0 \sin(kz - 2\pi \times 10^6 t) V m^{-1} \). The incorrect statement is:
One mole of an ideal monatomic gas undergoes a cyclic process. The total heat supplied to the gas is:
An electron is revolving in an excited state of Hydrogen with velocity \( \sqrt{25.6} \times 10^5 m/s \). The radius is \( x \times 10^{-9} m \). Find \( x \).
A car travels on a circular racetrack of radius \( 50 m \), which is banked at an angle \( \theta \). If the car travels at a speed \( 10 m s^{-1} \), then the wear and tear on its tyres is minimum. Taking the acceleration due to gravity to be \( 10 m s^{-2} \), the value of \( \theta \) is:
Three identical p-n junction diodes \( D_1, D_2, D_3 \) are connected across a battery as shown in the figure. If the width of the depletion regions of \( D_1 \), \( D_2 \), and \( D_3 \) are \( W_1 \), \( W_2 \), and \( W_3 \), respectively, then the correct option is:
The following table presents parts of the electromagnetic spectrum and their corresponding applications. The correct option is:
Bob B of mass \( m \) at rest is hanging vertically from the ceiling via a massless string of length \( 10 m \). A point mass A of mass \( m \) travelling horizontally with speed \( 10 m s^{-1} \) hits bob B elastically. The bob B rises by height \( h \) after collision. The value of \( h \) is:
An ideal gas is made of polyatomic molecules. Each of the molecules has three translational, three rotational and \( f \) number of vibrational modes. If the ratio of heat capacities \( C_p/C_v \) of the gas is \( 8/7 \), then the value of \( f \) is :
For the following reaction sequence, choose the correct option:
Given below are two statements:
Statement-I : \( [Fe(ox)_3]^{3-} \) is chiral.
Statement-II : \( trans-[Cr(H_2O)_2(ox)_2]^- \) is chiral.
(Given : \( oxH_2 = HOOC - COOH \))
In light of the above statements, choose the most appropriate answer from the options given below:
The following carbocation is stabilized by the interaction of the empty \( p \) orbital with:
In potash alum, the ratio of \( K^+ \) and \( SO_4^{2-} \) ions is:
The correct statement about peptides and proteins is:
The numbers \(17.0145\) and \(21.0235\) were rounded to three figures after the decimal point. The resulting numbers, respectively, are:
The correct order of solubility of the given salts in water at \( 298 K \) is: (with \( K_{sp} \) values given: \( AgBr = 5.0 \times 10^{-13} \), \( Zn(OH)_2 = 1.0 \times 10^{-15} \), \( Hg_2Cl_2 = 1.3 \times 10^{-18} \))
Among the following options, the correct trend in the electron gain enthalpy is:
Assertion A: For an ideal solution formed by mixing liquids P and Q, \(\Delta_{mix}H = 0\) and \(\Delta_{mix}V = 0\).
Reason R: No interactions occur between P and Q.
In the light of the above statements, choose the most appropriate answer from the options given below:
The amino acid that gives a red-blood colour on treating its sodium fusion extract with sodium nitroprusside is:
The standard electrode potential (\(E^\circ\)) for the half-cell reaction \(Fe^{3+} + e^- \rightarrow Fe^{2+}\) at \(298 K\) is: (Given: \(E^\circ(Fe^{3+}/Fe) = -0.04 V\) and \(E^\circ(Fe^{2+}/Fe) = -0.44 V\))
In an acidic medium, \(10 mL\) of \(0.25 M\) oxalic acid is titrated with \(KMnO_4\) solution. If the volume of \(KMnO_4\) solution required to reach end point is \(10 mL\), the strength of the \(KMnO_4\) solution is:
According to crystal field theory, the correct order of ligands with respect to their decreasing order of field strength is:
Two moles of an ideal gas undergo free expansion from \(10 L\) to \(100 L\) at \(300 K\). The values of \(\Delta S_{system}\) and \(\Delta S_{surroundings}\) are:
\(2A \xrightarrow{k} B\) is a zero-order reaction, where \(k = 1.0 mol L^{-1} min^{-1}\). If the initial concentration of A is \(2 M\), then the time taken to complete \(75%\) of the reaction will be:
Given below are two statements: One is labelled as Assertion A and the other is labelled as Reason R.
Assertion A: Generally, \( 3d \) transition metals have high melting points.
Reason R: Involvement of \( 3d \)-electrons in addition to \( 4s \)-electrons in the interatomic metallic bonding.
In light of the above statements, choose the most appropriate answer from the options given below:
For a salt XY, which is a strong electrolyte, the plot of \( \Lambda_m \) versus \( \sqrt{c} \) has a slope of \( -90.0 S cm^2 mol^{-3/2} L^{1/2} \) at \( 298 K \). At \( 0.01 M \) concentration of XY, the value of \( \Lambda_m \) is \( 145.0 S cm^2 mol^{-1} \). The limiting molar conductivity of \( Y^- \) ion (\( \lambda_{Y^-}^\circ \), in \( S cm^2 mol^{-1} \)) at \( 298 K \) will be (Given: \( \lambda_{X^+}^\circ = 74.0 S cm^2 mol^{-1} \)):
The amount of carbon dioxide evolved upon complete combustion of \( 116 g \) of n-butane is (Given: atomic mass in amu H = 1, C = 12 and O = 16):
For an elementary chemical reaction, the Arrhenius plot is given below. If the energy of activation is \( 6.64 kJ mol^{-1} \) and \( R = 8.3 J K^{-1} mol^{-1} \), the temperature at which the rate constant becomes \( e^2 min^{-1} \), is:
Given below are two statements:
Statement-I : Heating NaCl with concentrated \( H_2SO_4 \) and \( MnO_2 \) results in oxidation of Mn.
Statement-II : Heating NaI with concentrated \( H_2SO_4 \) and \( MnO_2 \) results in reduction of Mn.
In light of the above statements, choose the most appropriate answer from the options given below:
Among the species given below, the spin-only magnetic moment is highest for (Given: Atomic number of Ti = 22, Mn = 25, Fe = 26 and Co = 27):
The lanthanide ion having four unpaired electrons is (Given: Atomic numbers of Ce = 58, Nd = 60, Tb = 65 and Ho = 67):
The formula of tetraammineaquachloridocobalt(III) chloride is:
Consider the reversible processes for \(1.0 mol\) of an ideal gas as shown in the figure. Processes 2 and 4 are adiabatic. \(w_1\), \(w_2\), \(w_3\) and \(w_4\) represent work done (in calories) in the processes 1, 2, 3 and 4, respectively; \(\Delta U_2\) and \(\Delta U_4\) are changes in the internal energy for the processes 2 and 4, respectively. [use \(R = 2 cal K^{-1} mol^{-1}\)]. The correct option is:
Given below are two statements: One is labelled as Assertion A and the other is labelled as Reason R.
Assertion A: The first ionization enthalpy of O is lower than that of N and F.
Reason R: The loss of an electron from O leads to a stable half-filled \( p \) orbital.
In light of the above statements, choose the most appropriate answer from the options given below:
Consider the following statements about the solutions formed by mixing two liquids:
A. An ideal solution thus formed obeys Raoult’s law throughout the composition range.
B. Mixture of chloroform and acetone shows negative deviation from Raoult’s law.
C. Mixture of aniline and phenol shows positive deviation from Raoult’s law.
The correct option is:
One of the products formed in the following reaction of cyclohexylmagnesium bromide with cyclohexanamine is:
Step 1: Understanding the Concept:
Grignard reagents (\( RMgX \)) are highly reactive organometallic compounds. The carbon atom bonded to magnesium carries a substantial partial negative charge, behaving as a very strong base and a powerful nucleophile.
When mixed with any species containing an active, acidic hydrogen (like \( -OH, -NH_2, -SH, -COOH \)), a rapid acid-base neutralization reaction occurs preferentially over any nucleophilic addition.
Step 3: Detailed Explanation:
1. Identify the reactants:
- Cyclohexylmagnesium bromide: A Grignard reagent containing a highly basic cyclohexyl carbanion:
\[ C_6H_{11}^- Mg^{2+} Br^- \]
- Cyclohexanamine: A primary amine (\( R-NH_2 \)). The hydrogen atoms directly attached to the nitrogen are weakly acidic and easily abstracted by extremely strong bases.
2. Reaction pathway:
When these two compounds are mixed, the basic cyclohexyl carbanion abstracts an acidic proton from the amino group of cyclohexanamine:
\[ C_6H_{11}-MgBr + C_6H_{11}-NH_2 \rightarrow C_6H_{12} + C_6H_{11}-NH-MgBr \]
The carbanion captures the proton to form cyclohexane:
\[ C_6H_{11}^- + H^+ \rightarrow C_6H_{12} (Cyclohexane) \]
Step 4: Final Answer:
The primary organic product formed is cyclohexane, which corresponds to Option (D).
Quick Tip: Grignard reagents are extremely sensitive to any active hydrogen source.
Whenever a Grignard reagent (\( RMgX \)) reacts with water, alcohols, carboxylic acids, or primary/secondary amines, the major product is always simply the alkane (\( R-H \)) corresponding to the Grignard alkyl group.
The correct statement is:
A protein undergoes reversible thermal denaturation from its initial state N to denatured state D according to \(N \rightleftharpoons D\). At \(60^\circC\), the concentrations of both N and D are equal at equilibrium, and the standard enthalpy change of denaturation is \(666 kJ mol^{-1}\). The standard entropy change (\(\Delta S^\circ\) in \(kJ K^{-1}mol^{-1}\)) of the protein upon denaturation at \(60^\circC\) is closest to:
Match the species in List I with their geometry in List II:
Choose the correct answer from the options given below:
Given below are two statements :
Statement I : trans-But-2-ene upon treatment with \( Br_2 \) in \( CCl_4 \) gives the following product: (meso-2,3-dibromobutane).
Statement II : cis-But-2-ene upon treatment with alkaline \( KMnO_4 \) gives the following product: (meso-butane-2,3-diol).
In the light of the above statements, choose the most appropriate answer from the options given below:
Consider the following reaction sequences and choose the correct option:
The complex which has facial and meridional isomers is:
Identify the reactions which give aniline as the major product:
A. Reduction of benzonitrile with \(LiAlH_4\)
B. Hoffmann bromamide degradation of benzamide
C. Reduction of nitrobenzene with \(NaBH_4\)
D. Hydrolysis of acetanilide
Choose the correct answer from the options given below:
Step 1: Understanding the Concept:
Aniline is a primary aromatic amine (\( C_6H_5NH_2 \)).
To determine which reactions produce aniline as the major product, we must analyze the mechanisms and products of each reaction.
Step 3: Detailed Explanation:
Let us analyze each reaction in detail:
- Reaction A: Reduction of benzonitrile:
Benzonitrile (\( C_6H_5C\equiv N \)) is treated with the powerful reducing agent \( LiAlH_4 \). This reduces the nitrile group completely to a primary amine without breaking any carbon-carbon bonds:
\[ C_6H_5C\equiv N \xrightarrow{LiAlH_4} C_6H_5CH_2NH_2 (Benzylamine) \]
The product is benzylamine, not aniline. Thus, Reaction A is incorrect.
- Reaction B: Hoffmann bromamide degradation of benzamide:
Benzamide (\( C_6H_5CONH_2 \)) is treated with bromine in an aqueous or ethanolic solution of alkali (\( KOH \)):
\[ C_6H_5CONH_2 + Br_2 + 4KOH \rightarrow C_6H_5NH_2 (Aniline) + K_2CO_3 + 2KBr + 2H_2O \]
This reaction degrades the amide by removing the carbonyl carbon, directly producing aniline. Thus, Reaction B is correct.
- Reaction C: Reduction of nitrobenzene with \( NaBH_4 \):
Sodium borohydride (\( NaBH_4 \)) is a mild, highly selective reducing agent. It is not strong enough to reduce aromatic nitro groups (\( -NO_2 \)) to amines. Nitrobenzene remains unreacted under these conditions. Thus, Reaction C is incorrect.
- Reaction D: Hydrolysis of acetanilide:
Acetanilide (\( C_6H_5NHCOCH_3 \)) is a secondary amide. Heating it in the presence of an aqueous acid (\( HCl/H_2O \)) induces nucleophilic acyl substitution, leading to acidic hydrolysis:
\[ C_6H_5NHCOCH_3 + H_2O \xrightarrow[\Delta]{HCl} C_6H_5NH_3^+Cl^- + CH_3COOH \]
Upon standard alkaline workup, the anilinium chloride salt yields free aniline (\( C_6H_5NH_2 \)). Thus, Reaction D is correct.
Combining the correct reactions gives:
\[ B and D only \]
Step 4: Final Answer:
Reactions B and D produce aniline, which corresponds to Option (B).
Quick Tip: Remember:
- \( NaBH_4 \) is highly chemoselective and cannot reduce nitro groups, esters, or nitriles.
- Hoffmann degradation is a reliable method for converting primary amides to primary amines with one less carbon atom.
Match the vitamins in List I with their sources in List II:
Choose the correct answer from the options given below:
The correct decreasing order of oxidation state of the underlined atom in each molecule is:
(with N in \( N_2O_5 \), Al in \( Al_2O_3 \), and S in \( H_2S \) underlined)
The compound that CANNOT be obtained from the aldol condensation reaction shown below, is:
(where 3,3-dimethylcyclopentan-1-one is reacted with benzaldehyde in the presence of NaOH)
Among the following, the compound having conjugated double bonds is:
Given below are two statements:
Statement-I: Oxidation of p-nitrotoluene with acidic \( KMnO_4 \) gives an acid that is stronger than benzoic acid.
Statement-II: Reduction of p-nitrotoluene with Sn/HCl followed by neutralization gives an amine that is more basic than aniline.
In light of the above statements, choose the most appropriate answer from the options given below:
The green paramagnetic species formed by heating \( KMnO_4 \) at \( 513 K \) is:
Consider the following reaction, and choose the correct option.
(where toluene is reacted with chromyl chloride in the presence of \( CS_2 \), followed by acidic hydrolysis to yield compound P)
Step 1: Understanding the Concept:
The oxidation of toluene using chromyl chloride (\( CrO_2Cl_2 \)) in a non-polar solvent like \( CS_2 \), followed by hydrolysis, is a named reaction called the Etard Reaction.
This reaction selectively oxidizes the benzylic methyl group to an aldehyde, stopping at the benzaldehyde stage.
Step 3: Detailed Explanation:
- Step 1: Identify compound P:
The Etard reaction sequence is:
\[ C_6H_5CH_3 + 2CrO_2Cl_2 \xrightarrow{CS_2} C_6H_5CH[OCrCl_2OH]_2 \xrightarrow{H_3O^+} C_6H_5CHO (Benzaldehyde) \]
Thus, compound P is benzaldehyde (\( C_6H_5CHO \)).
- Step 2: Evaluate the options:
- Option (A): Saturated \( NaHCO_3 \) reacts with carboxylic acids to release \( CO_2 \) (brisk effervescence). Benzaldehyde is an aldehyde and does not react with sodium bicarbonate. Thus, (A) is incorrect.
- Option (B): Reacting benzene with acetyl chloride (\( CH_3COCl \)) in the presence of anhydrous \( AlCl_3 \) is a Friedel-Crafts acylation that yields acetophenone, not benzaldehyde. Thus, (B) is incorrect.
- Option (C): Phenols and anilines react with bromine water to form white precipitates due to rapid poly-bromination. Benzaldehyde is a deactivated aromatic system and does not form a white precipitate. Thus, (C) is incorrect.
- Option (D): Hydrogenation of benzoyl chloride (\( C_6H_5COCl \)) over \( Pd/BaSO_4 \) is known as the Rosenmund Reduction. This selective reduction converts the acid chloride group directly into an aldehyde, yielding benzaldehyde:
\[ C_6H_5COCl + H_2 \xrightarrow{Pd/BaSO_4} C_6H_5CHO + HCl \]
This statement is completely correct.
Step 4: Final Answer:
The correct option is (D).
Quick Tip: Connecting named reactions is highly common in entrance exams. Remember that both the Etard Reaction (oxidation of toluene) and the Rosenmund Reduction (reduction of benzoyl chloride) are primary synthetic routes to prepare benzaldehyde.
A 1:3 electrolyte in an aqueous solution is:
Consider the following schematic plots of orbital wavefunction (\( \psi_r \)) against distance (\( r \)) from the nucleus.
The figure representing two radial nodes in the orbital is:
Arrange the following compounds in the increasing order of polarity:
A. \( CH_3CH_2OCH_2CH_3 \) (Ether)
B. \( CH_3CH_2OH \) (Alcohol)
C. \( CH_3COCH_3 \) (Ketone)
D. \( CH_3COOH \) (Carboxylic acid)
Choose the correct answer from the options given below:
The highest occupied molecular orbital for \( Ne_2 \) is:
The number of vertebrae in an adult human is _________.
Symbiotic association between fungi and algae are called _________.
Cell theory was formulated by _________.
Which of the following are characteristics of prokaryotic cells?
(a) Ribosomes are made of 50S and 30S subunits
(b) They can have plasmids
(c) They contain mesosome
(d) They have peroxisomes
Choose the correct answer from the options given below:
Which of the following is not a part of human central neural system?
Mitochondrial inner membrane encloses_________.
Match List-I with List-II:
List-I: A. Cristae, B. Cisternae, C. Thylakoids, D. Phospholipid
List-II: I. Flat membrane sacs in stroma of chloroplast, II. Infoldings in mitochondria, III. Cell membrane, IV. Disc-shaped sacs in Golgi apparatus
Choose the correct answer from the options given below:
Step 1: Understanding the Concept:
Eukaryotic cell organelles and biological membranes contain distinct morphological structures that are specialized for their metabolic functions.
Step 3: Detailed Explanation:
Let us match the structural components with their descriptions:
1. Cristae (A): These are infoldings of the inner mitochondrial membrane that project into the matrix to increase surface area for the electron transport chain.
\[ Cristae (A) \rightarrow Infoldings in mitochondria (II) \]
2. Cisternae (B): These are flattened, disc-shaped membrane sacs stacked parallel to each other that make up the Golgi apparatus.
\[ Cisternae (B) \rightarrow Disc-shaped sacs in Golgi apparatus (IV) \]
3. Thylakoids (C): These are flattened membranous sacs arranged in grana within the stroma of chloroplasts that contain photosynthetic pigments.
\[ Thylakoids (C) \rightarrow Flat membrane sacs in stroma of chloroplast (I) \]
4. Phospholipid (D): Phospholipids are amphipathic lipid molecules that form the foundational bilayer of the cell plasma membrane.
\[ Phospholipid (D) \rightarrow Cell membrane (III) \]
Combining all the matches:
\[ A \rightarrow II, \quad B \rightarrow IV, \quad C \rightarrow I, \quad D \rightarrow III \]
Step 4: Final Answer:
The matching sequence corresponds to Option (B).
Quick Tip: To avoid confusion:
- {Cristae} are {Critical} for respiration (Mitochondria).
- {Cisternae} are {Cists} (sacs) for packaging (Golgi apparatus).
The plastid that stores xanthophyll is known as _________.
Which of the following statements related to pituitary gland are correct?
(a) It is divided anatomically into adenohypophysis and neurohypophysis
(b) It secretes follicle stimulating hormone
(c) It secretes melanocyte stimulating hormone
(d) It does not secrete prolactin
Choose the correct answer from the options given below:
Photorespiration reaction catalyzed by RuBPCo is shown below:
RuBP + O\(_2 \rightarrow\) 3-Phosphoglycerate + X
Identify "X" from the given options:
Mad cow disease is caused by __________.
Which pigment has absorption peak at 700 nm in the photosynthetic reaction centre PS I (P700)?
In water, frogs respire using __________.
Which of the following represents the correct sequence of arrangement of bones in the lower limb of humans?
Phyllotaxy is the pattern of arrangement of __________
Match List-I with List-II:
List-I: A. Starch, B. Antibody, C. Concanavalin A, D. Glut-4
List-II: I. Fights infection, II. Energy storage, III. Glucose transport, IV. Lectin
Choose the correct answer from the options given below:
Given below are two statements:
Statement I: When any plane passing through the central axis of the body divides the organism into two identical halves, it is called radial symmetry.
Statement II: In phylum Echinodermata, both adults and larvae are radially symmetrical.
In the light of the above statements, choose the most appropriate answer from the options given below:
Endomembrane system includes __________
How many molecules of pyruvic acid are produced at the end of glycolysis from 206 molecules of glucose?
Which of the following plant growth regulators is used as herbicide?
Given below are two statements:
Statement I: In gymnosperms, the male and female gametophytes remain within the sporangia.
Statement II: In gymnosperms, seeds are not covered.
In the light of the above statements, choose the most appropriate answer from the options given below:
Match List-I with List-II:
List-I: A. Spherical, B. Rod, C. Comma, D. Spiral
List-II: I. Vibrio, II. Cocci, III. Spirilla, IV. Bacilli
Choose the correct answer from the options given below:
Which of the following are characteristic features of Solanaceae family?
(a) Flowers are bisexual and actinomorphic
(b) Calyx have five sepals and are united
(c) Androecium have five stamens and are epipetalous
(d) Ovary is inferior
Choose the correct answer from the options given below:
Select the correct sequence of experiments that led to a gradual understanding of photosynthesis in green plants.
The number of action potentials generated by sino-atrial node (SAN) in a healthy human is __________ per minute.
How many turns of Calvin cycle are required for the formation of three molecules of glucose?
Which of the following statements is incorrect?
Match List-I with List-II:
List-I: A. Family, B. Genus, C. Class, D. Phylum, E. Order
List-II: I. Sapindales, II. Dicotyledonae, III. Anacardiaceae, IV. Angiospermae, V. Mangifera
Choose the correct answer from the options given below:
Arrange the following taxonomic categories in ascending order.
(a) Genus (b) Class (c) Order (d) Phylum (e) Family (f) Kingdom (g) Species
Choose the correct answer from the options given below:
Match List-I with List-II:
List-I: A. Marginal placentation, B. Axile placentation, C. Parietal placentation, D. Free central placentation
List-II: I. Argemone, II. Tomato, III. Primrose, IV. Pea
Choose the correct answer from the options given below:
Step 1: Understanding the Concept:
Placentation refers to the mode of arrangement of ovules within the ovary of a flower. It serves as an important taxonomic feature to distinguish between different plant families.
Step 3: Detailed Explanation:
Let us match the placentation types with their representative examples:
1. Marginal Placentation (A): The placenta forms a ridge along the ventral suture of the ovary, and ovules are borne on this ridge in two rows. Typical of Fabaceae. Example: Pea.
\[ Marginal (A) \rightarrow Pea (IV) \]
2. Axile Placentation (B): The placenta is axial, and the ovules are attached to it in a multilocular ovary. Typical of Solanaceae and Liliaceae. Example: Tomato.
\[ Axile (B) \rightarrow Tomato (II) \]
3. Parietal Placentation (C): The ovules develop on the inner wall of the ovary or on peripheral parts. Example: Argemone and Mustard.
\[ Parietal (C) \rightarrow Argemone (I) \]
4. Free Central Placentation (D): The ovules are borne on a central axis, and septa are absent. Example: Dianthus and Primrose.
\[ Free Central (D) \rightarrow Primrose (III) \]
Combining all the matches:
\[ A \rightarrow IV, \quad B \rightarrow II, \quad C \rightarrow I, \quad D \rightarrow III \]
Step 4: Final Answer:
The correct matching sequence corresponds to Option (D).
Quick Tip: A useful tip:
- In parietal placentation, a false septum called a replum can sometimes form (seen in Mustard).
- Basal placentation (ovule at the base of a unilocular ovary) is seen in Sunflower and Marigold.
Sphenopsida class belongs to __________
Which of the following statements regarding photorespiration are correct?
(a) Do not occur in \( C_3 \) plants
(b) \( CO_2 \) is consumed and \( O_2 \) is generated
(c) Phosphoglycolate is formed
(d) No synthesis of ATP and NADPH
Choose the correct answer from the options given below:
Smooth endoplasmic reticulum __________
Which one of the following statements is incorrect?
Genus represents __________
Which of the following is not a prokaryote?
Which of the following plant growth regulators promotes internode elongation prior to flowering in cabbage?
The correct sequence of adult cell cycle phases is __________
Match List-I with List-II:
List-I: A. Fusion of protoplasms between gametes, B. Fusion of two nuclei, C. Generation of haploid spores
List-II: I. Meiosis, II. Plasmogamy, III. Karyogamy
Choose the correct answer from the options given below:
Step 1: Understanding the Concept:
Sexual reproduction in fungi and other simple organisms involves a specific, highly regulated sequence of cellular and nuclear fusion events followed by a reduction division.
Step 3: Detailed Explanation:
Let us match the reproductive events with their correct terms:
1. Fusion of protoplasms between gametes (A): The physical joining of the cytoplasm of two motile or non-motile gametes without the immediate fusion of their nuclei is called plasmogamy.
\[ A \rightarrow Plasmogamy (II) \]
2. Fusion of two nuclei (B): The subsequent fusion of the two haploid nuclei to form a single diploid zygotic nucleus is called karyogamy.
\[ B \rightarrow Karyogamy (III) \]
3. Generation of haploid spores (C): The diploid zygote undergoes a reduction division (meiosis) to produce haploid sexual spores.
\[ C \rightarrow Meiosis (I) \]
Combining all the matches:
\[ A \rightarrow II, \quad B \rightarrow III, \quad C \rightarrow I \]
Step 4: Final Answer:
The matching sequence corresponds to Option (A).
Quick Tip: In some fungi (like Ascomycetes and Basidiomycetes), plasmogamy is not immediately followed by karyogamy. This leads to a long-lasting, unique phase containing two nuclei per cell, known as the dikaryotic phase (\( n + n \)).
Given below are two statements:
Statement I: The class name Reptilia refers to creeping or crawling mode of locomotion.
Statement II: All organisms belonging to Reptilia have three chambered heart.
In the light of the above statements, choose the most appropriate answer from the options given below:
Given below are two statements:
Statement I: Chromosomes are fully condensed at the end of prophase I.
Statement II: Meiosis II resembles mitosis.
In the light of the above statements, choose the most appropriate answer from the options given below:
Which of the following is not a characteristic of chordates?
Length of the stem at time 0 is 20 cm. The arithmetic growth rate is 30 cm per day. What is the length of the stem at the end of the 7th day?
Arrange the following elements in descending order of their contribution to percentage weight of the human body.
(a) Oxygen (b) Carbon (c) Hydrogen (d) Nitrogen
Choose the correct answer from the options given below:
Step 1: Understanding the Concept:
All living organisms are composed of various organic and inorganic elements.
The relative abundance of these major elements in the human body can be quantified as a percentage of total body weight.
Step 3: Detailed Explanation:
According to standard physiological data, the approximate elemental composition by mass in the human body is:
- Oxygen (O): \( \approx 65.0% \)
- Carbon (C): \( \approx 18.5% \)
- Hydrogen (H): \( \approx 10.5% \)
- Nitrogen (N): \( \approx 3.3% \)
Sorting these values from largest to smallest (descending order):
\[ 65.0% (Oxygen) > 18.5% (Carbon) > 10.5% (Hydrogen) > 3.3% (Nitrogen) \]
This gives the sequence:
\[ Oxygen (a) \rightarrow Carbon (b) \rightarrow Hydrogen (c) \rightarrow Nitrogen (d) \]
Step 4: Final Answer:
The descending order sequence is (a), (b), (c), (d), which corresponds to Option (A).
Quick Tip: Oxygen is the most abundant element by weight in both the human body and the Earth's crust. Carbon is the second most abundant in the body, reflecting the organic, carbon-based nature of life.
In frogs, the number of pairs of cranial nerves arising from the brain are __________
Which of the following is used as a clot buster?
The inactive form of Bt toxin is converted to the active form in the insect gut __________
Given below are two statements :
Statement I : Down’s syndrome is caused by the absence of one of the X-chromosomes.
Statement II : Turner’s syndrome is caused by the presence of an additional copy of the chromosomes.
In light of the above statements, choose the most appropriate answer from the options given below :
Which of the following disease is not sexually transmitted?
Sperm motility is due to __________
Natural selection can lead to
(a) stabilisation
(b) genetic drift
(c) directional change
(d) disruption
Choose the correct answer from the options given below:
The method of directly injecting a sperm into ovum in assisted reproductive technology is called :
Which of the following structure is not a part of the male reproductive system?
Arrange the following in descending order of number of species in the Amazonian rain forest.
(a) Plants (b) Birds (c) Fishes (d) Invertebrates (e) Mammals
Choose the correct answer from the options given below :
Given below are two statements:
Statement I: Ovulation is caused by LH surge leading to rupture of Graafian follicles.
Statement II: Graafian follicle remaining after ovulation transform into corpus luteum and secretes large amount of estrogen.
In the light of the above statements, choose the most appropriate answer from the options given below:
Which of the following are primary consumers in a food chain?
A population of diploid organisms is at Hardy-Weinberg equilibrium. If the frequency of allele A is 0.1, the frequency of AA is
Match List-I with List-II:
List-I: A. Excess growth hormone, B. Luteinizing hormone, C. Vasopressin, D. Oxytocin
List-II: I. Reabsorption of water and electrolytes in kidney, II. Contraction of uterus during child birth, III. Acromegaly, IV. Ovulation
Choose the correct answer from the options given below:
The opening between the right atrium and the right ventricle is guarded by
Sponges exchange O\(_2\) with CO\(_2\) by
How many theca are present in each lobe of a typical bilobed angiosperm anther?
Muscle contraction is initiated by a signal sent by the central nervous system by the release of
Which of the following statements about lac-operon is correct?
Which of the following in female gametophyte of an angiosperm helps in guiding the pollen tube for fertilizing the eggs?
Which of the following plant produces non-albuminous seeds?
If the diploid chromosome number of typical angiosperm is 36, what would be the chromosome number in its endosperm?
Which of the following statements about the reabsorption process in Henle’s loop are correct ?
(a) The descending limb of Henle’s loop is permeable to water but almost impermeable to electrolytes.
(b) Urine gets concentrated in Henle’s loop.
(c) Reabsorption of \( Na^+ \) and water takes place in Henle’s loop.
(d) Active or passive transport of electrolytes occurs in the ascending limb of Henle’s loop.
Choose the correct answer from the options given below :
Which of the following is the correct order of arrangement of vertebrate column from the head to toe ?
Which of the following is not evidence for evolution ?
Given below are two statements :
Statement I : Modern Homo sapiens arose in Africa and moved across continents.
Statement II : Homo sapiens arose around 75000 to 10000 years ago.
In the light of the above statements, choose the most appropriate answer from the options given below :
Consider a population of 10 million cells. Given the per-capita birth rate of 0.002 (per unit time) and the per-capita death rate of 0.002 (per unit time), the expected number of cells after 10 generations is:
During PCR, primers bind to the DNA strands in the ______ step.
Given below are two statements : one is labelled as Assertion A and the other is labelled as Reason R.
Assertion A : The logistic growth model of populations is considered more realistic than the exponential growth model.
Reason R : Resources are finite.
In the light of the above statements, choose the most appropriate answer from the options given below :
Adaptive radiation in placental mammals and Australian Marsupials leading to similarity between distant species is an example of
Which of the following are secondary lymphoid organs?
(a) Bone marrow (b) Tonsils (c) Spleen (d) Thymus
Choose the correct answer from the options given below :
Which of the following hormone is not secreted by human placenta ?
Which of the following enzymes synthesizes precursor mRNA ?
Given below are two statements :
Statement I : Plasmids are autonomously replicating DNA.
Statement II : Plasmids are extrachromosomal DNA.
In the light of the above statements, choose the most appropriate answer from the options given below :
For a person with blood group 'O', which of the following is not a possible combination of parents' blood group genotypes ?
Given below are two statements : one is labelled as Assertion A and the other is labelled as Reason R.
Assertion A : Forelimbs of human and bats are homologous.
Reason R : Forelimbs of humans and bats have similar anatomical structure.
In the light of the above statements, choose the most appropriate answer from the options given below :
Colostrum, secreted by mother during initial days of lactation, is abundant in
Given below are two statements : one is labelled as Assertion A and the other is labelled as Reason R.
Assertion A : Abingdon tortoise in Galapagos islands became extinct within a decade after goats were introduced.
Reason R : Goats were more efficient at browsing than Abingdon tortoise.
In the light of the above statements, choose the most appropriate answer from the options given below :
The covering of ovum at ovulation is
Match List-I with List-II:
List-I: A. Both species are harmed, B. One species is harmed and the other is benefited, C. Both species are benefited, D. One is benefited while the other has no effect
List-II: I. Predation, II. Mutualism, III. Competition, IV. Commensalism
Choose the correct answer from the options given below :
Given below are two statements : one is labelled as Assertion A and the other is labelled as Reason R.
Assertion A : In an experiment, Mendel observed that the F1 progeny plants are all tall and none are dwarf.
Reason R : Stem height is a contrasting trait, with tall being dominant and dwarf being recessive.
In the light of the above statements, choose the most appropriate answer from the options given below :
Given below are two statements : one is labelled as Assertion A and the other is labelled as Reason R.
Assertion A : In recombinant DNA technology, lysozyme is used for disrupting bacterial cells while cellulase is used for plant cells.
Reason R : Isolation of genetic material needs disruption of cells.
In the light of the above statements, choose the most appropriate answer from the options given below :
Which of the following is used as an effective sedative and painkiller for treating post-surgery patients ?
Which of the following statements are correct ?
(a) Energy flow from producers to consumers is unidirectional
(b) Energy pyramid can never be inverted
(c) Transfer of energy follows the 1% law
Choose the correct answer from the options given below :
Which of the following statements is correct about Plasmodium ?
Match List-I with List-II:
List-I: A. Transformation, B. Cloning site, C. Selection, D. Ori
List-II: I. Restriction enzyme, II. Transfer DNA to host bacteria, III. Replication, IV. Antibiotic
Choose the correct answer from the options given below :
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