First Order Reaction

Q. If $60\%$ of a first order reaction was completed in 60 min, $50\%$ of the same reaction would be completed in approximately [log 4 = 0.60, log 5 = 0.69

1. 40 min
2. 50 min
3. 45 min
4. 60 min

Q. In a 1st order reaction A $\to$products, the concentration of the reactant decreases to 6.25$\%$ of its initial value in 80 minutes. What is (i) the rate constant and (ii) the rate of reaction, 100 minutes after the start, if the initial concentration is 0.2 mole/litre?

1. $2.17\times {10}^{-2}mi{n}^{-1},3.47\times {10}^{-4}mol.litr{e}^{-1}mi{n}^{-1}$
2. $3.465\times {10}^{-2}mi{n}^{-1},2.166\times {10}^{-4}mol.litr{e}^{-1}mi{n}^{-1}$
3. $3.465\times {10}^{-3}mi{n}^{-1},2.17\times {10}^{-3}mol.litr{e}^{-1}mi{n}^{-1}$
4. $2.166\times {10}^{-3}mi{n}^{-1},2.667\times {10}^{-4}mol.litr{e}^{-1}mi{n}^{-1}$

Q.

In the reaction, P + Q ⟶ R + S

the time taken for 75% reaction of P is twice the time taken for 50% reaction of P. The concentration of Q varies with reaction time as shown in the figure. The overall order of the reaction is

1. 2

2. 3
3. 0
4. 1

Q.

Suresh wants to calculate the rate constant of a reaction. All the information he had is it is a first order reaction and average life period of the reaction is 2 hrs.Can you help him to find the rate constant of the reaction.

1. 0.5
2. 1.443
3. 0.693
4. 0.25

Q. Percentage of isotope Q1 is 23.4% and that of Q2 is 76.6% If Q2 is 8.082 times heavier than {}^{12}C and Q1 is 7.833 times heavier than {}^{12}C then molecualr mass of compound QO_{2 }will be approximately ________

Q. In the reaction, P + Q $\to$ R + S, the time taken form 75% reaction of P is twice the time taken for 50% reaction of P. The concentration of Q varies with reaction time as shown in the figure. The overall order of the reaction is :

1. 2
2. 3
3. 1
4. 0