General
✓✗The number of moles of oxygen atoms in 2 mol of H2SO4 is
- 16
- 2
- 8
- 4
General
✓✗Which of the following is a pure substance?
- Brass
- Air
- Distilled water
- Sea water
General
✓✗Dinitrogen and dihydrogen react to form ammonia. If 2.00 × 103 g of N2 reacts with 1.00 × 103 g of H2, the mass of ammonia formed is
- 3000 g
- 5670 g
- 2430 g
- 1000 g
General
✓✗What is the mass of the precipitate formed when 50 mL of a 16.9% (mass/volume) solution of AgNO3 is mixed with 50 mL of a 5.8% (mass/volume) NaCl solution? (Ag = 107.8, N = 14, O = 16, Na = 23, Cl = 35.5)
- 7 g
- 3.5 g
- 28 g
- 14 g
General
✓✗Which law is illustrated by the formation of SO2 and SO3 from sulphur and oxygen?
- Law of conservation of mass
- Avogadro's law
- Law of multiple proportions
- Law of definite proportions
General
✓✗A metal M forms a chloride containing 34.5% metal by mass. If the formula of the chloride is MCl3, the atomic mass of M is (Cl = 35.5)
- 27
- 52
- 34.5
- 56
General
✓✗The number of chloride ions in 0.1 mol of CaCl2 is
- 6.022 × 1023
- 1.204 × 1023
- 6.022 × 1022
- 3.011 × 1022
General
✓✗The number of neutrons in 1.8 g of H2O (taking only 1H and 16O) is
- 4.8 × 1023
- 6.0 × 1023
- 1.08 × 1024
- 4.8 × 1022
General
✓✗What mass of 95% pure CaCO3 will be required to neutralise 50 mL of 0.5 M HCl solution according to the reaction CaCO3(s) + 2HCl(aq) → CaCl2(aq) + CO2(g) + H2O(l)? (Calculate up to the second decimal place.)
- 1.32 g
- 3.65 g
- 1.25 g
- 9.50 g
General
✓✗Carbon and oxygen form two oxides containing 42.9% and 27.3% carbon respectively. The masses of oxygen combining with a fixed mass of carbon in the two oxides are in the ratio
- 2 : 1
- 1 : 2
- 3 : 8
- 1 : 1
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 percentage of hydrogen in water is about (H = 1, O = 16)
- 88.9%
- 11.1%
- 33.3%
- 5.6%
General
✓✗The molar mass of CuSO4·5H2O is (Cu = 63.5, S = 32, O = 16, H = 1)
- 159.5 g mol−1
- 231.5 g mol−1
- 177.5 g mol−1
- 249.5 g mol−1
General
✓✗10 g of hydrogen and 64 g of oxygen are filled in a steel vessel and exploded. The amount of water produced in this reaction is
- 4 mol
- 2 mol
- 3 mol
- 1 mol
General
✓✗An organic compound contains carbon, hydrogen and oxygen. Its elemental analysis gave C 38.71% and H 9.67%. The empirical formula of the compound is
- CH2O
- CH3O
- CH4O
- CHO