Learn more about the properties, composition, and structure of substances (elements and compounds) with these Chemistry questions and answers. This Test can be used by students preparing for Chemistry in JAMB, WAEC, NECO or Post UTME.
further heating
adding concentrated H2SO4
cooling the acid solution with cold water
bubbling air through the acid solution
Correct answer is D
Bubbling of air through the acid solution removes deposited oxides of nitrogen.
Nitric acid is prepared in the laboratory by heating a nitrate salt with the concentrated acid.
NaNO3 + H2SO4 → NaHSO4 + HNO3
Vapours of nitric acid are condensed to a brown liquid in a receiver cooled under cold water. "Dissolved oxides of nitrogen" e.g NO2 are removed by redistillation or blowing a current of carbondioxide or dry air through the warm acid
The gas that can be collected by downward displacement of air is
chlorine
sulphur (IV) oxide
carbon (IV) oxide
ammonia
Correct answer is D
Upward delivery works well for hydrogen and ammonia, which are both less densed than air. Sometimes, they are collected over water.
An oxide XO2 has a vapour density of 32. What is the atomic mass of X?
20
32
14
12
Correct answer is B
Molecular mass = vapour density X2
Mm of XO2 = x + 16(2) = x + 32
vapour density = 32
∴ x + 32 = 32 × 2
x + 32 = 64
x = 64 - 32
x = 32
∴ the relative molecular mass of X is 32
Relative molecular mass = vapour density × 2
According to Charle's law, the volume of a gas becomes zero at
−100°c
−273°c
−373°c
0°c
Correct answer is B
Where −273°c = OK
i.e −273°c + 273 = OK
At zero kelvin, the volume of a gas becomes zero.
The carbon atoms on ethane are
sp2 hybridized
sp3 hybridized
sp4 hybridized
sp hybridized
Correct answer is B
Alkane's family are sp3 hybridized