At STP, if 5.6 litres of a gas weights \(7.5 \mathrm{~g}\), then identify the gas.

At STP, if 5.6 litres of a gas weights \(7.5 \mathrm{~g}\), then identify the gas.
  1. \(\mathrm{CO}\)
  2. \(\mathrm{NO}\)
  3. \(\mathrm{NO}_2\)
  4. \(\mathrm{CO}_2\)

Solution

One mole of gas at STP occupies \(22.4 \mathrm{~L}\). Thus, 5.6 L of gas at STP contains 0.25 moles. Number of moles \(=\) weight in gram \(/\) molecular weight \(\begin{aligned} 0.25 & =7.5 / M \\ M & =30 \end{aligned}\) Thus, the gas is NO. Hence, the correct option is (b).

Asked in: AP EAMCET 2020 (21 Sep Shift 2)

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