Question

 A certain piece of wood contains 6g of C-14 whose half-life is 2400 years. After 7200 years, the amount of C-14 left in that piece of wood will be

3 g
1.5 g
0.75 g
none of these
​

Answer 1

Answer:

0.75g

Explanation:

A certain piece of wood contains 6g of C-14 whose half-life is 2400 years. After 7200 years, the amount of C-14 left in that piece of wood will be

3 g  

1.5 g  

0.75 g  

none of these

​

As half life = 2400 Years

In beginning wood contains = 6g

after 2400 years it will remain = 6/2 = 3 g

after next 2400 years ( total 4800 years) it will remain = 3/2 = 1.5 g

after further next 2400 years ( total 7200 Years) it will remain = 1.5/2 = 0.75 g

0.75g is right answer

or simply

Remaining weight = Initial weight / 2 ^(T/Half Life)

=> Remaining weight = 6/ 2 ^(7200/2400)

=> Remaining weight = 6 / 2³

=> Remaining weight = 6 /8

=> Remaining weight = 0.75 g