Leutium-176 has a half-life of 3.85 mc012-1.jpg 1010 years. after 1.155 mc012-2.jpg 1011 years, how much leutium-176 will remain from an original 16.8-g sample?
2.10 g
3.00 g
5.56 g
8.40 g

Answer : The amount left of leutium-176 will be, 2.10 g

Solution :

First we have to calculate the rate constant, we use the formula :

Now we have to calculate the amount left of the sample.

Expression for rate law for first order kinetics is given by :

where,

k = rate constant  =

t = decay time  =

a = initial amount of the sample = 16.8 g

a - x = amount left after decay process  = ?

Now put all the given values in above equation, we get

Therefore, the amount left of leutium-176 will be, 2.10 g