1993 - JAMB Chemistry Past Questions and Answers - page 1
1
Which of the following substances is a mixture?
A
Sulphur powder
B
Bronze
C
Distilled water
D
Ethanol
correct option: c
Users' Answers & Comments2
A balanced chemical equation obeys the law of?
A
conservation of mass
B
difinite proportions
C
multiple proportions
D
conservation of energy
correct option: a
Users' Answers & Comments3
How many moles of oxygen molecules would be produced from the decomposition of 2.50 moles of potassium trioxochlorate (V)?
A
2.50
B
3.50
C
3.75
D
7.50
correct option: c
2KClO3(s) → 2KCl(s) + 3O2(g)
From the above balanced equation, 2 moles of reactant decomposed to give 3 moles of O2 i.e.
i mole of reactant will produce (3)/(2) moles O2.
∴ 2.5 moles KClO3 will give
= 3.75 moles
Users' Answers & CommentsFrom the above balanced equation, 2 moles of reactant decomposed to give 3 moles of O2 i.e.
i mole of reactant will produce (3)/(2) moles O2.
∴ 2.5 moles KClO3 will give
= 3.75 moles
4
For iodine crystals to sublime on heating, the molecules must acquire energy that is?
A
less than the forces odf attraction in the solid
B
equal to the forces of attraction in th solid
C
necessary to melt the solid
D
greater than the forces of attraction in both the solid and the liquid phases
correct option: d
Users' Answers & Comments5
An element, E, has the electronic configuration 1s22s22p63s2p3. The reaction of E with a halogen X can give?
A
EX3 and EX5
B
EX3 only
C
EX5 only
D
EX2 and EX3
correct option: a
Users' Answers & Comments6
Two atoms represented as U and U are?
A
isomers
B
allotropes
C
isotopes
D
anomers
correct option: c
Users' Answers & Comments7
As the difference in electronegativity between bonded atoms increases, polarity of the bond?
A
decreases
B
increases
C
remains unchanged
D
reduces to zero
8
Which group of elements forms hydrides that are pyramidal in structure?
A
III
B
IV
C
V
D
VI
correct option: c
Users' Answers & Comments9
Water has a rather high boiling point despite its low molecular mass because of the presence of?
A
hydrogen bonding
B
covalent bonding
C
ionic bonding
D
metallic bonding
correct option: a
Users' Answers & Comments10
Argon is used in gas-filled electric lamp because it helps to?
A
prevent the reduction of the lamp fillaments
B
prevent oxidation of the lamp fillaments
C
make the lamp fillament glow brightly
D
keep the atmosphere in the lamp inert
correct option: c
Users' Answers & Comments