Chemical Kinetics Question 263
Question: For a chemical reaction $ {t_{1/2}} $ is 2.5 hours at room temperature. How much of the reactant will be left after 7.5 hours if initial weight of reactant was 160g-
Options:
A) 10 g
B) 40 g
C) 80 g
D) 20 g
Show Answer
Answer:
Correct Answer: D
Solution:
[d] Using the relation $ [ A ]={{[ A ]} _0}{{(1/2)}^{n}} $ [n =number of half-lives $ T=n\times {t _{1/2}} $
Here, $ n=\frac{7.5}{2.5}=3 $
$ \therefore [A]=160\times {{( \frac{1}{2} )}^{3}}=160\times \frac{1}{8}=20g $
