Please check for Class 12 - Biology Important Questions

### List of Questions and Answers

1.For a reaction 3A -> 2B, the concentration of B increases from 0.4 mol L-1 to 0.7 mol l -1 in 3 minutes. The rate of reaction during this interval is :
(A) 0.033 mol L-1 min-1
(B) 0.05 mol L-1 min-1
(C) 0.1 mol L-1 min-1
(D) 0.3 mol L-1 min-1

Ans: (B) 0.05 mol L-1 min-1

2. The first order decomposition of a certain gas has an initial rate of 216 atm s-1.The rate after 25 percent decomposition of the gas is:
(A) 54 atm s-1
(B) 108 atm s-1
(C) 162 atm s-1
(D) 216 atm s-1

Ans: (C) 162 atm s-1

3. At a temperature of T=300K there are 30% molecules with kinetic energy greater than the acivation energy. According to Arrhenius equation, the fraction of the molecules which will have kinetic energy greater than the activation energy at 150K [Assume that the activation energy is independent of temperature] is:
(A) 0.09
(B) 0.15
(C) 0.30
(D) 0.90

Ans: (A) 0.09

4. Which property does NOT change on addition of a catalyst ?
(A) Activation energy
(B) Rate Constant
(C) Reaction mechanics
(D) Equilibrium constant

Ans: (D) Equilibrium constant

5. The reaction 2A -> B follows zero order kinetics with rate constant k.The slope of the plot of concentration of A against time is :
(A) -2k
(B) -k
(C) -k/2
(D) k

Ans: (A) -2k