Question

Mass of proton is 1.67×10^-27kg.How many protons would make 1mg?

Answer 1

Answer:

Mass of proton (m) = 1.67×10^(-27) kg.

Since, 1 kg = 1000 g

Therefore, m = 1.67x10^(-27+3) g = 1.67x10^(-24) g

Let N no. of protons be present in 1 g. Hence, Nxm = 1 g

So, N = 1 / m = 1 / (1.67x10^(-24))

N = 6x10^(23) (approx.)

Exact mass of proton gives N = 6.022 x 10^(23).

That is a very special no. In fact, it is the Avogadro’s constant used frequently in chemistry. Avogadro’s no. is actually the number of atoms in exactly 12 g of C-12 isotope of carbon. Since, the atomic mass of C-12 is 12 u (unified mass), then again the no. of carbon atoms turn out to be N.

Explanation: