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.
Sieving is a technique used to separate mixtures containing solid particles of
small sizes
large sizes
different sizes
the same size
Correct answer is C
Sieving is a simple and convenient technique of separating particles of different sizes.
If the molecular mass of tetraoxosulphate (VI) acid is 98, calculate its vapour density.
196
49
106
82
Correct answer is B
Molecular mass = Vapour Density x 2
Vapour Density = Molecular Mass2
Where Molecular mass = 98g/mol
Vapour Density = 982
Vapour Density = 49g/mol
Which of these alloys contains copper?
solder
steel
permallory
bronze
Correct answer is D
Bronze is an alloy consisting primarily of copper, commonly with about 12% tin and often with the addition of other metals (such as aluminium, manganese, nickel or zinc) and sometimes non-metals or metalloids such as arsenic, phosphorus or silicon.
Calculate the percentage composition of oxygen in calcium trioxocarbonate(IV) [Ca=40, C=12, O=16]
16
48
40
12
Correct answer is B
Calcium trioxocarbonate (IV) = CaCO3
Percentage of Oxygen = Molar mass of 3OMolar mass ofCaCO3 × 100%
Percentage of Oxygen = (3×16)(40+12+48) x 100%
Percentage of Oxygen = 48100 x 100%
Percentage of Oxygen = 48%
The ionic radii of metals are usually
greater than their atomic radii
unaffected by the charge on the ion
the same as their atomic radii
less than their atomic radii
Correct answer is D
In a neutral atom, the atomic and ionic radius is the same, but many elements exist as anions or cations. If the atom loses its outermost electron (positively charged or cation), the ionic radius is smaller than the atomic radius because the atom loses an electron energy shell.
Yes ionic radius is only less than atomic radius for a metal.