Question

The atomic mass of calcium is 40g. The number of calcium atoms is 0.4g of calcium is:- [a] 6.022 x 10^10 [b] 6.022 x 10^22 [c] 6.022 x 10^23 [d] 6.022 x 10^21

Answer 1

the answer is d.6.022 *10*21

Answer 2

Hi there!!

Given mass of calcium is 0.4 grams.

Molar mass of calcium is 40 grams.

So we have a formula to calculate the no: of moles

$No : of moles = \frac{Given.mass}{Molar.mass}$

= $\frac{0.4}{40}$

= 0.01 moles

Also , to calculate the no: of particles ,we have a formula :

No: of particles = No: of moles × Avogadro no:

We can use this formula to calculate the no: of atoms , no: of molecules , and no: of ions:

No: of calcium atoms = 0.01 × 6.022 ×10²³
= 0.06022×10²³ atoms