Question

Three-fourth of a radioactive material decays in 2.5 days. How long will it take for `15//16th` of the material to decay?
a. 2 days b. 5 days c. 7.5 days d. 10 days
A. a. 2 days
B. b. 5 days
C. c. 7.5 days
D. c. 7.5 days

Answer 1

Correct Answer - b. 5 days
`(t_(15//16))/(t_(3//4)) = ("log"(a_(0))/(a_(0) - x))/("log" (a_(0))/(a_(0) - x_(1)))`
`("log" (a_(0))/(a_(0) - x))/("log" (a_(0))/(a_(0)//14)) implies ("log"16)/(log4) = (4)/(2)`
`:.t_(15//16) = t_(3//4) xx 2`
`= 2.5 xx 2 = 5`