Gas G identified by CuO reduction and volume-based molar mass Steps: - G reduces CuO to pink-brown copper, so G acts as a reducing agent; from options, only CO and H₂ qualify. - At RTP, 1 mol gas occupies 24 dm³, so 1 g of G (1.2 dm³) contains 1.2/24 = 0.05 mol. - Molar mass of G = 1 g / 0.05 mol = 20 g/mol. - H₂ (molar mass 2 g/mol) would occupy 24/2 = 12 dm³ per 1 g, far exceeding 1.2 dm³, so eliminate H₂. - CO (molar mass 28 g/mol) fits as the reducing gas with molar mass near 20 g/mol. Why A is correct: - CO reduces CuO to Cu per the reaction 2CuO + 2CO → 2Cu + 2CO₂, and its molar mass yields ~0.86 dm³ per 1 g at RTP, aligning with observed volume. Why the others are wrong: - B. H₂ occupies ~12 dm³ per 1 g at RTP, not 1.2 dm³. - C. N₂ is inert and does not reduce CuO. - D. NO does not reduce CuO to copper …