Question

Please solve q 9?

Answer 1

`6.022 × 10^20\ "molecules"`

Explanation:

• `"1 cm"^3 = 10^-3\ "dm"^3`
• `"1 mol"` of any gas at STP occupies `"22.4 dm"^3` of volume
• `"1 mol = 6.022 × 10"^23\ "molecules"`

Volume of dinitrogen gas (in `"dm"^3`)

`22.4 cancel("cm"^3) × (10^-3\ "dm"^3)/(1 cancel("cm"^3)) = 22.4 × 10^-3\ "dm"^3`

Number of moles of dinitrogen

`cancel(22.4) xx 10^-3 cancel("dm"^3) × "1 mol"/(cancel(22.4) cancel("dm"^3)) = 10^-3\ "mol"`

Number of molecules

`10^-3 cancel"mol" × (6.022 × 10^23\ "molecules")/(1 cancel"mol") = 6.022 × 10^20\ "molecules"`