Chemistry Past Questions and Answers

The salt that reacts with dilute hydrochloric acid to produce a pungent smelling gas which decolourizes acidified purple potassium tetraoxomanganate (VII) solution is

A Na₂SO₄
B Na₂SO₃
C Na₂S
D Na₂CO₃

Question 32:

A pair of compounds that can be used to generate a gas which has physiological effect on human beings is

A Sodium trioxonitrate (V) and calcium chloride
B Sodium dioxonitrate (III) and ammonium chloride
C Sodium trioxonitrate (V) and ammonium chloride
D Sodium dioxonitrate (III) and potassium chloride

Question 33:

Hydrogen is used in oxy-hydrogen flames for melting metals because it

A Evolves a lot of heat when burnt
B Combines explosively with oxygen
C Is a very light gas
D Is a rocket fuel

Question 34:

What properties of duralumin make it more useful than its constituent metals?

A It is heavy with a high melting point
B It is malleable and has high density
C It is strong and light
D It is hard and ductile

Question 35:

The pair of metals in the reactivity series that are usually extracted by the electrolysis of their ores is

A Magnesium and zinc
B Magnesium and calcium
C Copper and zinc
D Lead and calcium