Question

How many helium atoms are in a 12.0 g sample?

Answer 1

The correct answer is 2.99 helium atoms.


I hoped this helped!

Answer 2

Answer: The number of helium atoms present are $18.066\times 10^{23}$

Explanation:

To calculate the number of moles, we use the equation:

$\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}$

Given mass of helium = 12.0 g

Molar mass of helium = 4 g/mol

Putting values in above equation, we get:

$\text{Moles of helium}=\frac{12.0g}{4g/mol}=3mol$

According to mole concept:

1 mole of an element contains $6.022\time 10^{23}$  number of atoms.

So, 3 moles of helium will contain = $3\times 6.022\times 10^{23}=18.066\times 10^{23}$ number of atoms.

Hence, the number of helium atoms present are $18.066\times 10^{23}$