Waec Chemistry 1999 Past Questions and Answers

Question 21:

• WAEC 1999

Helium is preferred to hydrogen in filling balloons because hydrogen

A. Is inflammable
B. Is diatomic
C. Exhibits isotopy
D. Is a component of water

Question 22:

• WAEC 1999

30cm³ pf hydrogen at s.t.p combine with 20cm³ of oxygen to form steam according to the following equation 2H_2(g) + O_2(g) → 2H₂O_(g). Calculate the total volume of the gaseous mixture at the end of the reaction

A. 50cm³
B. 35cm³
C. 30cm³
D. 25cm³

Question 23:

• WAEC 1999

An exothermic reaction is one which involves

A. Attainment of dynamic equilibrium
B. Loss of heat to the surrounding
C. Evolution of gas as it proceeds
D. Positive change in value of enthalpy

Question 24:

• WAEC 1999

Which of the following is an acid salt?

A. NH₄CI
B. MgSO₄ 7H₂O
C. CH₃COONa
D. NaHCO₃

Question 25:

• WAEC 1999

Which of the following compounds dissolves in water to form a solution with pH below 7?

A. Sodium tetraoxosulphate (VI)
B. Potassium hydroxide
C. Ammonium chloride
D. Sodium trioxocarbonate (IV)