What is the mass of [tex]2.5 \times 10^{24}[/tex] atoms of Ne?

Given:
- Molar mass of Ne: [tex]20.18 \, \text{g/mol}[/tex]
- 1 mole = [tex]6.02 \times 10^{23}[/tex] atoms

A. 0.21 g Ne
B. 4.2 g Ne
C. 84 g Ne
D. [tex]1.5 \times 10^{40}[/tex] g Ne



Answer :

To find the mass of [tex]\( 2.5 \times 10^{24} \)[/tex] atoms of Neon (Ne), we need to follow these steps:

### 1. Determine the number of moles of Neon:
Firstly, the number of moles can be found using Avogadro's number, which is [tex]\( 6.02 \times 10^{23} \)[/tex] atoms per mole.

The formula to find the number of moles is:
[tex]\[ \text{Number of moles} = \frac{\text{Number of atoms}}{\text{Avogadro's number}} \][/tex]

Given:
[tex]\[ \text{Number of atoms} = 2.5 \times 10^{24} \][/tex]
[tex]\[ \text{Avogadro's number} = 6.02 \times 10^{23} \text{ atoms/mol} \][/tex]

Substitute these values into the formula:
[tex]\[ \text{Number of moles of Ne} = \frac{2.5 \times 10^{24}}{6.02 \times 10^{23}} \approx 4.15 \text{ moles} \][/tex]

### 2. Calculate the mass of the Neon using the number of moles and molar mass:
To find the mass of Neon, we use the molar mass of Neon, which is [tex]\( 20.18 \)[/tex] grams per mole.

The formula to find the mass is:
[tex]\[ \text{Mass} = \text{Number of moles} \times \text{Molar mass} \][/tex]

We have:
[tex]\[ \text{Number of moles} \approx 4.15 \text{ moles} \][/tex]
[tex]\[ \text{Molar mass} = 20.18 \text{ g/mol} \][/tex]

Substitute these values into the formula:
[tex]\[ \text{Mass of Ne} = 4.15 \text{ moles} \times 20.18 \text{ g/mol} \approx 83.8 \text{ grams} \][/tex]

Thus, the mass of [tex]\( 2.5 \times 10^{24} \)[/tex] atoms of Neon is approximately:

[tex]\[ 83.8 \text{ grams} \][/tex]

### Final Answer
Therefore, the closest option given is:
C. [tex]\( 84 \)[/tex] g Ne