  # Number of atoms present in 120 amu of Ca are

By BYJU'S Exam Prep

Updated on: September 13th, 2023 Given that the mass of calcium is 120 amu

We have to find the number of atoms present in 120 amu of Ca.

We know that number of moles = number of atoms/Avogadro number = given mass/Molar mass

i.e., Number of moles = N₀ / Nₐ = W/M

Table of content We know that 1 amu = 1.66056 x 10-24 g

So, 120 amu of Ca = 120 x 1.66056 x 10-24 g

Nₐ = 6.022 x 1023

Also, the molar mass of calcium = 40

Now, N₀ / 6.022 x 1023 = 120 x 1.66056 x 10-24 / 40

N₀ / 6.022 x 1023 = 3 x 1.66056 x 10-24

N₀ = 3 x 1.66056 x 10-24 x 6.022 x 1023

= 3 x 9.999 x 10-1

= 3 x 9.999/10

= 3 x 0.999

= 3 x 1

= 3

Therefore, the required number of atoms is 3.

Summary:

## The number of atoms present in 120 amu of Ca is

The number of atoms present in 120 amu of Ca is 3.

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