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39-CHEM-1-Basic Chemistry Topic 1 Mole Concept Objective Questions I (Only one correct option) 4. The most abundant elements by mass in the body of a healthy human adult are Oxygen (61.4%); Carbon (22.9%), Hydrogen (10.0 %); and Nitrogen (2.6%). The weight which a 75 kg person would gain if all “H atoms are replaced by 2H atoms is (2017 JEE Main) (a) 1Skg = (b)37.5kg (ce) 7.5 kg (d) lOkg 1. Given, abundance of clements by mass oxygen = 6L4%, carbon = 22.9%, hydrogen = 10% and nitrogen = 2.6% Total weight of person = 75kg Mass duc to 'H = 35 «10 =75kg "H atoms are replaced by 7H atoms. Mass due to 7H = (7.5 2)kg -. Mass gain by person = 7.5 kg 2. | g of a carbonate (M,CQy,) on treatment with excess HCl produces 0.01186 mole of CO,. The molar mass of M,CO, in gmol” ‘is (2017 JEE Main) (a) 1186 (b) 84.3 (c) 118.6 (d) 11,86 2. M,CO,+2HCI—> 2M Cl+ H,0+ CO, lg 0.01186 mole Number of moles of /,CO, reacted = Number of moles of CO, evolved 4 = 0.01186 [Af = molar mass of M;CO] = 84.3¢ mol”! M= ! 0.01186 3. At 300 K and | atm. 15 mL of a gascous hydrocarbon requires 375 mL air containing 20% O, by volume for complete combustion. After combustion, the gases occupy 330 mL. Assuming that the water formed is in liquid furm and the volumes were measured at the same temperature and pressure, the formula of the hydrocarbon is (2016 JEE Main) (a)GH, — (b) CH, (c) CyHig (d) C,H, 3. CHyg)+ (++ | 0.(g) —> «CO, (g) + SHO a 73 mL. 30m. 
