An organic compound contains 72% carbon, 12% hydrogen and 16% oxygen by mass. The empirical formula of the compound is
- A. C8H22O3
- B. C6H10O3
- C. C12H12O
- D. C6H12O
- E. C3H6O
Which of the following conduct electricity?
- A. sulfur
- B. graphite
- C. diamond
- D. red phosphorus
- E. yellow phosphorus
When 50cm3 of a saturated solution of sugar (molar mass 342.0g) at 40oC was evaporated to dryness, 34.2g of dry solid was obtained. The solubility of sugar at 40oC is
- A. 10.0 moles dm-3
- B. 7.0 moles dm-3
- C. 3.5 moles dm-3
- D. 2.0 moles dm-3
Which of the following groups of physical properties increases from left to right of the periodic table?
i. Ionization energy ii. Atomic radius iii. Electronegativity iv. Electron affinity
- A. i and ii
- B. i, ii and iii
- C. iii and iv
- D. i, iii and iv
An element with atomic number twelve is likely to be
- A. electrovalent with a velocity of 1
- B. electrovalent with a valency of 2
- C. covalent with a valency of 2
- D. covalent with valency of 4
The relationship between the velocity (U) of gas molecules and their relative molecular mass (M) is shown by the equation
- A. U = (kM)\(\frac{1}{2}\)
- B. U = (kM)2
- C. U = \(\sqrt{\frac{k}{m}}\)
- D. U = \(\frac{k}{m}\)
How much of magnesium is required to react with 260cm3 of 0.5 M HCl? [Mg = 24]
- A. 0.3g
- B. 1.5g
- C. 2.4g
- D. 3.0g
The number of atoms of chlorine present in 5.85g of NaCl is [Avogaro’s Number = 6.02 x 1023]
- A. 6.02 x 1022
- B. 5.85 x 1023
- C. 6.02 x 1023
- D. 5.85 x 1024
10cm3 of hydrogen fluoride gas react with 5cm3 of dinitrogen difluoride gas (N2F2) to form 103 of a single gas. Which of the following is the most likely equation of the reaction?
- A. HF + N2F2 \(\to\) N2HF3
- B. 2HF + N2F2 \(\to\) 2NHF2
- C. 2HF + N2F2 \(\to\) N2H2F3
- D. HF + 2N2F2 \(\to\) N4HF2
The Avogadro number of 24g of magnesium is the same as that of
- A. 1g of hydrogen molecules
- B. 16g of oxygen molecules
- C. 32g of oxygen molecules
- D. 35.5g of chlorine molecules
CO(g) + H2O(g) \(\to\) \(CO_{2g}\) + H2(g) \(\Delta\)H = -4100J. Which of the following factors favour the formation of hydrogen in the above reaction? i. high pressure. ii. low pressure iii. high-temperature iv. use of excess steam
- A. i, iii and iv
- B. iii only
- C. ii, iii and i
- D. iv only
The nucleus of the isotopes tritium,contains
- A. two neutrons with no protons
- B. one neutron and one proton
- C. two neutrons and one proton
- D. two neutrons, one proton and one electron
Which of the following is a measure of the average kinetic energy of the molecules of a substance?
- A. volume
- B. mass
- C. pressure
- D. temperature
A given mass of gas occupies 2 dm2 at 300k. At what temperature will its volume be doubled keeping the pressure constant?
- A. 400k
- B. 480k
- C. 550k
- D. 600k
The fraction of crude oil used as jet fuel is
- A. refinery gas
- B. diesel oil
- C. kerosine
- D. gasoline
At 25oC and 1atm, a gas occupies a volume of 1.50dm3. What volume will it occupy at 100oC and 1atm?
- A. 1.88 dm3
- B. 6.00 dm3
- C. 18.80 dm3
- D. 18.80 dm3
- E. 60.00dm3
The dissolution of common salt in water is a physical change because
- A. the salt can be obtained by crystallization
- B. the salt can be recovered by the evaporation of water
- C. heat is not generated during mixing
- D. the solution will not boil at 100oC
From the above diagram; The caustic soda in the conical flask serves to
- A. dry ethene gas
- B. remove carbon (iv) oxides from ethene
- C. remove carbon (ii) oxide from ethene
- D. remove sulphur (iv) oxide from ethene
When sodium ethanoate is treated with a few drops of concentrated tetraoxosulphate(vi)acid. one of the products is
- A. CH3COOH
- B. CH3COOCH3
- C. CH3COOC2H5
- D. C2H5COOCH3
Clothes should be properly rinsed with water after bleaching because
- A. the bleach decolourizes the clothes
- B. chlorine reacts with fabrics during bleaching
- C. the clothes are sterilized during bleaching
- D. hydrogen chloride solution is produced during bleaching
which of these metals CANNOT replace hydrogen from alkaline solutions?
- A. Aluminium
- B. Zinc
- C. Tin
- D. Iron