For a first-order reaction, the time required to reduce the concentration of the reactant to half its initial value is:

• (A) \(0.3010/k \)
• (B) \(1/k \)
• (C) \(0.693/k \)
• (D) \(2.303/k \)

The EAN of cobalt in the complex \( [Co(NH_3)_6]^{3+} \) is:

• (A) \(27 \)
• (B) \(30 \)
• (C) \(33 \)
• (D) \(36 \)

A cube of edge \(4\) cm has mass \(256\) g. The density of the material in SI unit is:

• (A) \(4 \,kg/m^3 \)
• (B) \(1600 \,kg/m^3 \)
• (C) \(4000 \,kg/m^3 \)
• (D) \(1000 \,kg/m^3 \)

The Van't Hoff factor for a solution of \( K_2SO_4 \) in water is:

• (A) \(1 \)
• (B) \(2 \)
• (C) \(3 \)
• (D) \(4 \)

In the electrolysis of molten NaCl, the product obtained at the cathode is:

• (A) Cl gas
• (B) Na metal
• (C) NaOH
• (D) H gas

Which of the following is an example of physisorption?

• (A) Adsorption of NH\(_3\) on charcoal
• (B) Adsorption of H on Ni
• (C) Adsorption of noble gases on solid surface
• (D) Adsorption of O on heated metal

Which of the following reagents are used in Friedel–Crafts alkylation?

• (A) \( AlCl_3 \)
• (B) \( FeCl_3 \)
• (C) \( RCOCl \)
• (D) \( H_2SO_4 \)