Half life

Q. ${}_2^{M}A\left(g\right){\to }_{Z-4}^{M-8}B\left(g\right)+\alpha -particles$
The radioactive disintegration follows first order kinetics. Starting with 1 mol of in a 1 litre closed flask at ${27}^{\circ }$C, pressure set up after two half-lives is approximately

1. 40 atm
2. 25 atm
3. 12 atm
4. 37 atm

Q. The half life period for a first order reaction is 69.3s. Its rate constant is

1. ${10}^{-2}{s}^{-1}$
2. ${10}^{-4}{s}^{-1}$
3. $10s^{-1}$
4. ${10}^2{s}^{-1}$

Q. Starting with one mole of a compound X, it is found that the reaction is $\frac{3}{4}$, complete in 1 min. What is the rate constant if the reaction follows first order?

1. $2.31s^{-1}$
2. $0.0231s^{-1}$
3. $0.231s^{-1}$
4. $2.31\times {10}^{-3}s-1$

Q. The half life of a first order reaction is

1. Independent of the initial concentration of the reactant
2. Directly proportional to the initial concentration of the reactant
3. Inversely proportional to the initial concentration of the reactant
4. Directly proportional to the square of the initial concentration of the reactant

Q. If $75\%$ of a first order reaction was completed in $90$ minutes, $60\%$ of the same reaction would be completed in approximately (in minutes)
(Take: $log2=0.30;log2.5=0.40)$
[Report tour answer to closest integer]

Q. Half-life of a reaction is found to be inversely proportional to the cube of initial concentration. The order reaction is

1. 2
2. 5
3. 3
4. 4

Q. The rate of a first order reaction is $0.69\times {10}^{-2}mi{n}^{-1}$and the initial concentration is 0.5 mol/L. The half life period is

1. 3000 s
2. 0.33 s
3. 50 s
4. 100 s

Q. A first order reaction is half completed in 45 minutes. How long does it need for 99.9% of the reaction to be completed?

1. 20 hours
2. 10 hours
3. 7.5 hours
4. 5 hours

Q. If half-life period for a first order reaction is 2 min. The rate constant is

1. $1.386mi{n}^{-1}$
2. $0.5mi{n}^{-1}$
3. $0.3465mi{n}^{-1}$
4. $2mi{n}^{-1}$

Q. If 8 g of a radioactive isotope has a half life period of 10 hrs, the half-life period of 2g of the same substance is

1. 5 hrs
2. 2.5 hrs
3. 40 hrs
4. 10 hrs