The half life period of a first order reaction is given by (where, K = rate constant) ?

Related Mcqs:

1. Rate constant for a first order reaction does not depend upon reaction time, extent of reaction and the initial concentration of reactants; but it is a function of reaction temperature. In a chemical reaction, the time required to reduce the concentration of reactant from 100 gm moles/litre to 50 gm moles/litre is same as that required to reduce it from 2 gm moles/litre to 1 gm mole/litre in the same volume. Then the order of this reaction is ?

   A. 0
   B. 1
   C. 2
   D. 3

2. The rate expression for a heterogeneous catalytic reaction is given by, – rA = K.KA PA(1 + KA.PA + KR.PR), where K is surface reaction rate constant and KA and KR are absorption equilibrium constants of A and R respectively. If KR PR >> (1 + KA PA), the apparent activation energy EA is equal to (given E is the activation energy for the reaction and ΔHR and ΔHA are the activation energies of adsorption of R and A) ?

   A. E
   B. E + ΔHA
   C. E + ΔHA – ΔHR)
   D. ΔHA + ΔHR

3. For a vapour phase catalytic reaction (A + B → P) which follows the Ridel mechanism and the reaction step is rate controlling, the rate of reaction is given by (reaction rate is irreversible, product also absorbs) ?

   A. -rA = (k . PA . PB)/(1 + KAPA + KPPP)
   B. -rA = (k . PA
   2 – k1PP)/(1 + KAPA + KPPP)
   C. -rA = (k . PA . PB)/(1 + KAPB + KBPB . KPPP)
   D. -rA = (k . PA . PB)/(1 + KAPA)

4. The rate controlling step for the heterogeneous irreversible catalytic reaction A(g) + B(g) → C(g) is the surface reaction of absorbed A with absorbed B to give adsorbed C. The rate expression for this reaction can then be written as (where, KA, KB and KC are the equilibrium constants and is the rate constant of the rate controlling step) ?

   A. k KA pApB / (1 + KApA + KBpB)
   B. k KAKB pApB / (1 + KApA + KBpB)
   C. k KAKB pApB / (1 + KApA + KBpB + KCpC)
   D. k KAKB pApB / (1 + KApA + KBpB + KCpC)2

5. Half life period of a chemical reaction is proportional to CA0 -1, if the reaction is of _______________ order?

   A. First
   B. Zero
   C. Second
   D. Third

6. A first order gaseous phase reaction is catalysed by a non-porous solid. The kinetic rate constant and the external mass transfer co-efficients are k and kg respectively. The effective rate constant (keff) is given by________________?

   A. keff = k + kg
   B. keff = (k+ kg)/2
   C. keff = (kkg)1/2
   D. 1/keff = 1/k + 1/kg

7. In a chemical reaction, represented by as shown in the bellow figure, it is observed that the (i) Rate of reaction increases by a factor of 4 on doubling the concentration of the reactant. (ii) Rate of reaction increases by a factor of 9 on trebling the concentration of the reactant. Then the rate of the reaction is proportional to(where, CA = concentration of the reactant)_____________________?

   A. CA
   B. CA2
   C. CA3
   D. CA4

8. The rate equation for the reaction represented by as shown in the bellow figure, is given by – rx = K1 . Cx/(1 + K2 Cx). At high value of Cx (i.e.., K2Cx > > 1), the order of the reaction and the rate constant are respectively___________________?

   A. Zero order & K1/K2
   B. Zero order & K1
   C. First order & K1
   D. First order & K1/K2

9. The knowledge of initial concentration and rate constant is necessary to determine the half life time of a reaction of _______________ order?

   A. Zero
   B. First
   C. Second
   D. None of these

10. The rate of a gas phase reaction is given by K . CA . CB. If the volume of the reaction vessel is reduced to l/4th of its initial volume, then the reaction rate compared to the original rate will be _______________ times?

    A. 4
    B. 16
    C. 8
    D. 2