MHT CET 2025 22nd April Evening Shift | Chemical Kinetics Question 7 | Chemistry

The half life values for two different first order reaction A and B are 75 minute and 2.5 hour respectively. What is the $\frac{r_B}{r_A}$ ratio of rate constants?

2.0

0.5

14.2

22.0

MHT CET 2025 22nd April Morning Shift

MCQ (Single Correct Answer)

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Nitric oxide reacts with $\mathrm{H}_2$ according to reaction. $2 \mathrm{NO}_{(\mathrm{g})}+2 \mathrm{H}_{2(\mathrm{~g})} \rightarrow \mathrm{N}_{2(\mathrm{~g})}+2 \mathrm{H}_2 \mathrm{O}_{(\mathrm{g})}$, identify correct relation for disappearance of reactant and appearance of product.

$\frac{1}{2} \frac{\mathrm{~d}[\mathrm{NO}]}{\mathrm{dt}}=-\frac{\mathrm{d}\left[\mathrm{H}_2\right]}{\mathrm{dt}}$

$\frac{\mathrm{d}\left[\mathrm{N}_2\right]}{\mathrm{dt}}=\frac{1}{2} \frac{\mathrm{~d}\left[\mathrm{H}_2 \mathrm{O}\right]}{\mathrm{dt}}$

$-\frac{\mathrm{d}\left[\mathrm{N}_2\right]}{\mathrm{dt}}=\frac{1}{2} \frac{\mathrm{~d}\left[\mathrm{H}_2 \mathrm{O}\right]}{\mathrm{dt}}$

$\frac{\mathrm{d}\left[\mathrm{H}_2\right]}{\mathrm{dt}}=-\frac{1}{2} \frac{\mathrm{~d}\left[\mathrm{~N}_2\right]}{\mathrm{dt}}$

MHT CET 2025 22nd April Morning Shift

MCQ (Single Correct Answer)

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Rate law for the reaction $\mathrm{aA}+\mathrm{bB} \rightarrow \mathrm{cC}+\mathrm{dD}$ is $r=k[A][B]$, the rate of reaction doubles if

Concentration of both A and B are doubled.

Concentration of A is doubled and concentration of B is kept constant.

Concentration of B is doubled and concentration of A is halved.

Concentration of A is kept constant and concentration of B is halved.

MHT CET 2025 22nd April Morning Shift

MCQ (Single Correct Answer)

-0

Half life of a first order reaction is 20 minutes. The time taken to reduce the initial concentration of reactant to $(1 / 10)^{\text {th }}$ is _________

46.60 min

66.46 min

79.68 min

88.00 min

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