Question

The number of neutrons present in 7 mg of C14 is
(1) 2.4x1024 (2) 8.6 x 1022
(3) 1.9 x 1018
(4) 9.7 x 1020​

Answer 1

Explanation:

7 mg = 0.007 g

So, No of moles of C-14 = 0.007g / 14 g/mole = 0.0005 moles

So No of C-14 atoms in 0.0005 moles = 0.0005 x 6.022 x 1023 atoms

= 3.00 x 1020

In 1 C-14 there are 8 neutrons, so total neutrons = 8 x 3.00 x 1020 = 2.4 x 1021

so the ans is (1)