Question

The highest number of helium atoms is in:

विकल्प

• 4 g of helium

• 2.271098 L of helium at STP

• 4 mol of helium

• 4 u of helium

Answer 1

4 mol of helium

Explanation:

1. In 4g:

Number of He atoms = No. of moles × N_A

= `("Mass"/"Molar mass") xx N_A`

= `(4/4) xx 6.022 xx 10^23`

= 6.022 × 10²³ atoms

2. In 2.271098 L of helium at STP:

Number of He atoms = `(2.271098/22.4) xx N_A`

= 0.1013 × 6.022 × 10²³

= 0.6105 × 10²³ atoms

3. In 4 mol of helium:

Number of He atoms = Number of moles × N_A

= 4 × 6.022 × 10²³ F

= 24.088 × 6.022 × 10²³ atoms

4. In 4u of Helium = 4u = 4 × 1.67 × 10⁻²⁴ gm

Number of atoms = Number of moles × N_A

= `(4 xx 1.67 xx 10^-24 gm)/4 xx 6.022 xx 10^23`

= 1 atom

Hence, the highest number of He atoms are in 4 mol He.