If half-life of a substance is 5 yrs, then the total amount of substance left after 15 years, when initial amount is 64 grams is
A.
16 grams
B.
2 grams
C.
32 grams
D.
8 grams.
Answer :
8 grams.
Solution :
$${t_{\frac{1}{2}}} = 5$$ years, $$T = 15$$ years hence total number of half life periods $$ = \frac{{15}}{5} = 3.$$
$$\therefore \,\,{\text{Amount}}\,{\text{left}} = \frac{{64}}{{{{\left( 2 \right)}^3}}} = 8g$$
Releted MCQ Question on Physical Chemistry >> Chemical Kinetics
Releted Question 1
If uranium (mass number 238 and atomic number 92) emits an $$\alpha $$ -particle, the product has mass no. and atomic no.