There is a 30 g sample of be-11 it has a half life of about 14 seconds how much will be left after 28 seconds

Answer : The amount left after 28 seconds will be, 7.505 grams

Solution :

As we know that the radioactive decays follow the first order kinetics.

First we have to calculate the half life of a Be-11.

Formula used :

Putting value of 'half-life' in this formula, we get the value of 'k'.

The expression for rate law for first order kinetics is given by :

where,

k = rate constant  = 0.0495

t = time taken for decay process  = 28 s

a = initial amount of the reactant  = 30 g

a - x = amount left after decay process  = ?

Now put all the given values in this formula, we get the amount left after decay.

Therefore, the amount left after 28 seconds will be, 7.505 grams.