UNN Chemistry 2019/2020 Past Questions

Practice each question, then open it to see the full details.

A common characteristic shared by iron and aluminium is that both

A.show oxidation states of +2 and +3
B.form soluble hydroxide
C.form only basic oxide
D.extracted by reduction

Pure substances are obtained by

A.extraction
B.evaporation
C.distillation
D.condensation

A solution of sodium trioxocarbonate(IV)contains 10.6g in 250cm³ of soluttion. Calculate the concentration of the solution.[${Na_2CO_3 = 106.0}$]

A.0.4moldm^-3
B.1.0moldm^-3
C.10.6moldm^-3
D.25.0moldm^-3

How many moles of limestone will be required to produce 5.6g of CaO? [ Ca=40, C=12, 0 =16].

A.0.20 mol
B.0.10 mol
C.1.12 mol
D.0.56 mol.

When water boilers are used for a long period of time, the solid substances left behind as scale are

A.magne-sium trioxosilicate (IV) and trust
B.magnesium trioxosilicate (IV) and calcium tetraoxosulphate (VI)
C.clay and magnesium trioxosilicate (IV)
D.clay and rust

The general methods of preparing salts include
i. neutralization ii. Precipitation iii. Double decomposition

A.i & ii
B.iii & iv
C.i, ii, iii, iv, & v
D.i, ii, iii & iv

How many isomers can be obtained from C₄H₁₀?

A.0
B.1
C.2
D.3

The minimum amount of energy required for a reaction to take place is

A.activation energy
B.kinetic energy
C.lattice energy
D.ionization energy

Which of the following gases dissolves in water vapour to produce acid rain during rainfall?

A.Oxygen
B.Carbon (II) oxide
C.Nitrogen
D.Sulphur (IV) oxide

The oxidation state of S in Ca(HSO₃)₂ is ..........

A.+2
B.-2
C.+4
D.-4

The inert gases are __ in water.

A.sparingly soluble
B.insoluble
C.soluble
D.none of the above

The luster of a metal is due to ___.

A.its high density
B.its high polishing
C.its chemical inverter
D.presence of free electrons

25cm³ of a gas x contain z molecules at 1500c and 75mmHg. How many molecules will 25cm³ of another gas y contain at the same temperature and pressure?

A.2y
B.2z
C.z
D.y

An oxide XO₂ has a vapour density of 32. What is the atomic mass of X?

A.32
B.20
C.14
D.12

The process of converting start to ethanol is known as

A.distillation
B.cracking
C.fermentation
D.oxidation