General
✓✗Which of the following has the highest percentage of carbon? (C = 12, H = 1, O = 16)
- CH3OH
- C2H2
- C2H6
- CH4
General
✓✗Which of the following has the same mass as 1 mol of O2? (S = 32, O = 16, C = 12, N = 14, H = 1)
- 1 mol of N2
- 1 mol of SO2
- 0.5 mol of SO2
- 1 mol of CH4
General
✓✗An element X has the following isotopic composition: 200X : 90%, 199X : 8.0%, 202X : 2.0%. The weighted average atomic mass of the naturally occurring element X is closest to
- 201 amu
- 199 amu
- 202 amu
- 200 amu
General
✓✗The mass of iron produced from 1.6 kg of Fe2O3 on complete reduction is (Fe = 56, O = 16)
- 2.24 kg
- 1.6 kg
- 0.56 kg
- 1.12 kg
General
✓✗The law stating that equal volumes of all gases at the same temperature and pressure contain equal numbers of molecules is
- Avogadro's law
- Gay-Lussac's law
- the law of definite proportions
- Boyle's law
General
✓✗How many molecules are present in 1 mL of water? (density 1 g mL−1)
- 3.35 × 1022
- 3.35 × 1023
- 6.02 × 1023
- 1.81 × 1022
General
✓✗A compound X contains 32% of A, 20% of B and the remaining percentage of C. The empirical formula of X is (atomic masses: A = 64, B = 40, C = 32 u)
- ABC3
- AB2C2
- A2BC2
- ABC4
General
✓✗Two samples of copper oxide gave the following results: 1.375 g of oxide A gave 1.098 g of copper, and 1.179 g of oxide B gave 0.942 g of copper on reduction. These results illustrate the law of
- reciprocal proportions
- gaseous volumes
- constant proportions
- multiple proportions
General
✓✗The volume of hydrogen at STP liberated when 2.4 g of magnesium reacts with excess dilute HCl is (Mg = 24)
- 1.12 L
- 22.4 L
- 2.24 L
- 4.48 L
General
✓✗A compound with empirical formula CH2O has a vapour density of 30. Its molecular formula is
- C3H6O3
- C2H4O2
- CH2O
- C6H12O6
General
✓✗Insulin contains 3.4% sulphur by mass. The minimum molar mass of insulin is (S = 32)
- 1882 g mol−1
- 3400 g mol−1
- 109 g mol−1
- 941 g mol−1
General
✓✗A compound contains 1.5 mol of element A and 2.0 mol of element B combined with each other. The empirical formula of the compound is
- A2B3
- AB2
- A4B3
- A3B4
General
✓✗In the reaction 2CO + O2 → 2CO2, 40 mL of CO is exploded with 30 mL of O2. The total volume of gas after the reaction (same temperature and pressure) is
- 40 mL
- 50 mL
- 70 mL
- 60 mL
General
✓✗The number of moles of oxygen in 1 L of air containing 21% oxygen by volume, under standard conditions, is nearest to
- 0.21 mol
- 0.0093 mol
- 2.10 mol
- 0.186 mol
General
✓✗The number of moles in 36 g of water is
- 1
- 0.5
- 18
- 2