Chemistry Past Questions And Answers
Which of the following gases has a characteristic pungent smell, turns red litmus paper blue and forms dense white fumes with hydrogen chloride gas?
- A) N2
- B) N2O
- C) CI2
- D) NH3
Dry hydrogen chloride when dissolved in methylbenzene
- A. turns blue litmus paper red
- B. turns red litmus paper blue
- C. does not affect litmus paper
- D. bleaches litmus paper
(a) Distinguish between molecular formula and structural formula
(b) List three factors that determine the ionization energy of an atom.
(c) State the two conditions necessary for the establishment of a chemical equilibrium
(d) Consider the following table
| Element | A | B | C |
| Ionization energy KJ mol\(^{-1}\) | 619 | 518 | 594 |
(d)(i) State which of the elements is the strongest reducing agent.
(ii) Give a reason for the answer stated in (d)(i)
(e) State Graham's law of diffusion
(f) Consider the following salts: Mg(NO\(_{3}\))\(_{2}\), CaCO\(_{3}\), Na\(_{2}\)SO\(_{4}\). State which of the salts is/are:
(i) readily soluble in water:
(ii) insoluble in water.
(g) Classily each of the following products as addition polymer or condensation polymer:
(i) protein:
(ii) perspex:
(iii) nylon.
(h) Define atomic radius.
(i) Explain briefly why ethanol has a higher boiling point than propane even though they both have comparable molar masses.
(j) State three significance of thepHvalue in everyday life.
View Discussion (0)WAEC 2021 THEORYThe chemicals used to soften hard water involves the addition of
- A) insoluble sodium compounds which from soluble solutions of calcium and magesium
- B) solube soudium compounds which from soluble solutions of calcium and magnesium ions
- C) solube sodium compounds which from insoluble precipitates of calcium and magnesium ions
- D) insoluble precipitates of calcium and magnesium ions
The collision theory proposes that
- A. reactants collide more frequently to bring about reduction in the reaction rate
- B. all collisions of reactants are effective
- C. reactants must collide with a certain minimum amount of energy to from products
- D. the fewer the collisions the faster the reaction rate
Consider the following reaction equation: C16H34 → C5H12 + C11H22. The process represented by the equation is
- A. cracking
- B. fermentation
- C. polymerization
- D. reforming
The soft solder used for welding and plumbing is alloy of
- A. lead and tin
- B. iron and tin
- C. lead and zinc
- D. iron and zinc
Which of the following methods can be used to obtain pure water from a mixture of sand, water and methanoic acid?
- A) netralization with NaOHfoolowed by filtration
- B) neutralization with NaOH followed by distillation
- C) fractional distillation
- D) filtration followed by distillation
All these are electromagnetic waves except
- A) White light
- B) Photon
- C) X-ray
- D) Infrared
The property of chlorine which causes hydrogen chloride to be more ionic than the chlorine molecules is its
- A. electrovalency
- B. electron affinity
- C. electropositivity
- D. electronegativity