Question

The half-life of a radioisotope is 1.5 hours. If its initial mass is 32g, the mass left undecayed after 6 hours is
A. 32 g
B. 16 g
C. 4 g
D. 2g

Answer 1

Correct Answer - D
`N="mass left" =(N_(0)("initial mass"))/(2^(t)//^(t)_(1//2)`
`N=32//2^(4)("since "t//_(t_(1//2))=6//_(1.5)=4)=2g`