The decay constant of a radioactive sample is λ. The half-life and mean life of the sample are, respectively

• $\frac{1}{\mathrm{\lambda }}; \ln \frac{2}{\mathrm{\lambda }}$

• $\ln \frac{2}{\mathrm{\lambda }}; \frac{1}{\mathrm{\lambda }}$

• $\mathrm{\lambda } \ln 2; \frac{1}{\mathrm{\lambda }}$

• $\frac{\mathrm{\lambda }}{\ln 2}; \frac{1}{\mathrm{\lambda }}$

32.

Which of the following is a first order reaction?

• NH₄NO₂ →N₂ + 2H₂O

• 2HI → H₂ + I₂

• 2NO₂ → 2NO + O₂

• 2NO + O₂ → 2NO₂

In the reaction of A + 2B → C + 2D, the initial rate = $-\frac{\mathrm{d}\left[\mathrm{A}\right]}{\mathrm{dt}}$ att = 0 wasfound to be 2.6 × 10^-2 M s^-1. What is the value of $-\frac{\mathrm{d}\left[\mathrm{B}\right]}{\mathrm{dt}}$ at t = 0 in Ms^-1 ?

• 2.6 × 10^-2

• 5.2 × 10^-2

• 1.0 × 10^-1

• 6.5 × 10^-3

Copper sulphate solution is electrolysed using copper electrode. The reaction taking place at anode is

• H⁺ + e^- → H

• SO${}_4^{2-}$ (aq) → SO₄ + 2e^-

• Cu²⁺ + 2e^- → Cu

• Cu (s) → Cu²⁺ (aq) + 2e-

How many cc of oxygen will be liberated by 2 A current flowing for 3 min 13 s through acidulated water?

• 11.2 cc

• 33.6 cc

• 44.8 cc

• 22.4 cc

Which of the following will have the highest coagulating power for As₂S₃ colloid?

• PO${}_4^{3-}$

• SO${}_4^{2-}$

• Al³⁺

• Na⁺

Adsorption is multilayer in the case of

• physical adsorption

• chemisorption

• Both (a) and (b)

• None of the above

In blast furnace, iron oxide is reduced by

• silica

• CO

• C

• limestone

In electrorefining of metal, the impure metal is made the anode and a strip of pure metal the cathode during the electrolysis of an aqueous solution of a complex metal salt. This method cannot be used for refining of

• silver

• copper

• aluminium

• zinc

Hypochlorous acid is

• HOCl

• HClO₂

• HClO₃

• HClO₄