2017 - JAMB Chemistry Past Questions & Answers - page 1

1
The general formula of alkanones is
A
RCHO
B
R2CO
C
RCOOH
D
RCOOR
CORRECT OPTION: b
Alkanones also known as ketones have the general formula R2CO
2
The constituent common to duralumin and alnico is
A
Co
B
Mn
C
Al
D
Mg
CORRECT OPTION: c
Constituents of duralumin are: Al, Cu, Mg, Mn.
Constituents of Alnico are: Al, Ni and Co

In 1909, the alloy of duralumin was discovered by Alfred Wilon consisting of 94% Al, 4% Cu, 1% Mg and 1% Mn(Manganese)
Alnico is an acronym referring to a family of iron alloys which in addition to iron are composed primarily of Al, Ni and Co.
3
The shape of the S-orbital is
A
elliptical
B
spiral
C
circular
D
spherical
CORRECT OPTION: d
The shape of the S-orbital is spherical.
4
Aluminium hydroxide is used in the dyeing industry as a
A
dye
B
dispersant
C
salt
D
mordant
CORRECT OPTION: d
Aluminium hydroxide is used in the dyeing industry as a mordant. It combines with a dye and thereby fixes it in a material.
5
The tincture of iodine means iodine dissolved in
A
ethanol
B
bromine chloride
C
chlorine water
D
water
CORRECT OPTION: a
It is also called weak iodine solution. Tincture solutions are characterized by the presence of alcohol.
6
Temporary hard water is formed when rain water containing dissolved carbon(IV) oxide flows over deposits of
A
CaCO3
B
Na2CO3
C
Na2SO4
D
CaSO4
CORRECT OPTION: a
Permanent hardness in water= Mg & Ca Sulphate.
Temporary hardness in water= Mg & Ca Carbonate.

Temporary hardness of water is caused by Magnesium and calcium hydrogencarbonate. It is formed when rainwater containing dissolved CO2 flows over deposit of CaCO3

i.e CaCO3 + CO2 + H2O → Ca(HCO3)2
7
The acid anhydride that will produce weak acid in water is
A
SO3
B
NO2
C
SO2
D
CO2
CORRECT OPTION: d
H2CO3 is an example of a weak acid while H2SO4 and HNO3 are examples of a strong acid.

CO2 combines with water to give a weak trioxocarbonate (IV) acid.

CO2 + H2O → H2CO3
8
The process that occurs when two equivalent forms of a compound are in equilibrium is
A
Isotopy
B
Resonance
C
Isomerism
D
Reforming
CORRECT OPTION: b
Resonance involves two forms of a compound.
Isomerism involves two or more forms of an element.
Reforming involves the rearrangement of molecule.

This deals with a two forms of a molecule where the chemical connectivity is the same but the electrons are distributed differently around the structure.
9
In the laboratory preparation of ethyl ethanoate, the water present in the mixture is removed using a solution of
A
an hydrous CaCl4
B
concentrated NaCO4
C
dilute NaOH
D
concentrated H4SO4
CORRECT OPTION: d
This is used in the preparation of ethyl ethanoate to remove the water present since it serves as a dehydrated agent.
10
The constituent of air necessary in the rusting process are
A
O2 and H2O
B
Ar and CO2
C
CO2 and H2O
D
O2 and CO2
CORRECT OPTION: d
The constituent of air includes O2, CO2, N2 and Noble gases. While for a rusting process to take place, the presence of O2, H2O and CO2 is important.

The constituent of air includes O2, CO2, N2 and Noble gases and for rusting process to take place.

The presence of O2 and CO2 as a constituent of air is indispensable
Pages: