Chemistry Past Questions and Answers

A small quantity of solid ammonium chloride (NH4Cl) was heated gently in a test tube, the solid gradually disappears to produce two gases. Later, a white cloudy deposit was observed on the cooler part of the test tube. The ammonium chloride is said to have undergone

A Distillation
B Sublimation
C Precipitation
D Evaporation
E Decomposition

Question 7:

Elements P, Q, R, S have 6, 11, 15, 17 electrons respectively, therefore,

A P will form an electrovalent bond with R
B Q will form a covalent bond with S
C R will form an electrovalent bond with S
D Q will form an electrovalent bond with S
E Q will form a covalent bond with R

Question 8:

An element X forms the following compounds with chlorine; XCl4, XCl3, XCl2. This illustrates the

A Law of multiple proportions
B Law of chemical proportions
C Law of simple proportions
D Law of conservation of mass
E Law of definite proportions

Question 9:

The oxidation state of chlorine in potassium chlorate is

A +1
B +2
C +3
D +5
E +7

Question 10:

When air which contains the gases Oxygen, nitrogen, carbondioxide, water vapour and the rare gases, is passed through alkaline pyrogallol and then over quicklime, the only gases left are;

A Nitrogen and carbon dioxide
B The rare gases
C Nitrogen and oxygen
D Nitrogen and the rare gases
E Nitrogen, carbondioxide and the rare gases