Waec 1989 Chemistry Past Questions And Answers
50cm 3 of a saturated solution of potassium trioxonitrate (V)at 40°C contains 5.05g of the salt. What is the solubility of potassium trioxonitrate (V) at 40°C? (KNO3 = 101)
- A. 1.0 mol/dm3
- B. 1.5mol/dm3
- C. 2.0mol/dm3
- D. 2.5mol/dm3
The oxidation number of chlorine is + 1 in
- A. KCIO3
- B. NaCIO
- C. HCI
- D. ZnCI2
The major raw material used in a plastic industry is
- A. ethanol
- B. sulphur.
- C. methylethanoate
- D. ethene
Which of the following store properties of cathode rays? They
- A. flow from the cathods to the anode
- B. travel in straight lines and cast a shadow of an object placed in their path.
- D. are negatively charged
- D. All of the above
Given the following half-cell reaction; 2Cl(aq) → CI2(g) + 2e, how many mole of electrons will be required to produce 1.12dm3of chlorine gas at s.t.p? (Molar volume of a gas at s.t.p. = 22.4dm3)
- A. 1.00
- B. 0.40
- C. 0.20
- D. 0.10
Which of the following gases will bleach moist litmus paper?
- A. Cl2
- B. Co2
- C. So3
- D. HCl
Given that for the reaction. N2(g) + 3H2(g) ⇌ 2NH3(g) if enthalphy change = -92kJ. What is the enthalpy of formation of ammonia from its elements?
- A. -46KJ mol-1
- B. -184KJmol-1
- C. -92KJmol-1
- D. 184KJmol-1
The following are s-block elements except
- A. lithium
- B. magnesium
- C. potassium
- E. aluminium
Which of the following statements best explains cracking? It is a process
- A. in which an alkene adds on itself repeatedly to form long-chain polymers.
- B. in which large hydrocarbon molecules are broken into smaller units.
- C. for measuring the octane number of petrol.
- D. in which carbon chain results in a zig-zag arrangement
1989 Given that 1 mole of carbon -12 weighs 12.0g, how many atoms are there in 24.0g magnesium? (C = 12, Mg = 24, NA = 6.02 x 10 23mol-1)
- A. 1/2 x 6.02 x1023
- B. 1 x 6.02 x1023
- C. 2 x 6.02 x 10 2323
- D. 3x 6.02 x 10 2323