2004 - JAMB Chemistry Past Questions & Answers - page 1

1
When a solid substance disappears completely as a gas on heating, the substance is said to have undergone
A
evaporation
B
distillation
C
crystallization
D
sublimation
CORRECT OPTION: d
2
A chemical reaction is always associated with
A
an increase in the composition of one of the substance
B
a change in the volume of the reactants
C
a change in the nature of the reactants
D
the formation of new substance
CORRECT OPTION: d
3
If a solution contains 4.9g of tetraoxosulphate (VI) acid, calculate the amount of copper (II) oxide that will react with it
[Cu = 64, O = 16, S = 32, H = 1]
A
0.8g
B
4.0g
C
40.0g
D
80.0g
CORRECT OPTION: b
Equation of the reaction
H2SO4(g) + CuO(s) → Cu4(aq) + H2O
Relative molecular mass of H2SO4 = 1 + 2 + 32 + 16 + 4 = 98
Relative molecular mass of CuO = 64 + 16 =80
From the above equation, 98s of H2SO4 reacts with 80s of CuO.
∴ 4.9g of H2SO4 will react with
= (4.9 * 80)/98 of CuO = 392/98 = 4.0g
4
What volume of gas is evolved at S.t.p if 2g of calcium trioxocarbonate (IV) is added to a solution of hydrochloric acid?
[Ca = 40, C = 12, O = 16, Cl = 35.5, H = 1 Molar volume of agas at s.t.p = 22.4 dm3
A
112 cm2
B
224 cm2
C
448 cm2
D
2240 cm2
CORRECT OPTION: c
CaCO3(s) + 2HCl(aq) → CaCl2 + H2O(l) + CO2
The relative molecular mass of CaCO3 = 40 + 12 + 16 * 3 = 52 +48 = 100 ; Relative molecular mass of CO2 = 12 + 10 * 2 = 44
From the above equation, 100g of CaCO3reacts with 44g of CO2 at s.t.p. i.e 22.4 dm3
2g of CaCO3 will react with (2*22.4)/100 of CO2 = 0.448 dm3
0.448 dm3 = 0.448 * 1000 = 448cm3
5
According to charles' law, the volume of a gas becomes zero at
A
0 oC
B
-100 oC
C
-273 oC
D
-373 oC
CORRECT OPTION: c
6
It is difficult to achieve an orderly arrangement of the molecules of a gas because they
A
have no definite shape
B
have little force of attraction between them
C
can collide with one another in the container
D
are too small in size
CORRECT OPTION: c
7
A given volume of methane diffuses in 20s. How long will it take the same volume of sulphur (IV) oxide to diffuse under the same conditions?
[C = 12, H = 1, S = 32, O = 16
A
5s
B
20s
C
40s
D
60s
CORRECT OPTION: c
Relative molecular mass of CH4 = 12 * 1 + 4 = 16
Relative molecular mass of SO2 = 32 + 10 *2 = 64
tSO2/tCH4 = √MSO2/MCH4
t/20 = √64/16 = √4
t/20 = 2
∴ t = 20 * 2 = 40sec
8
An electron can be added to a halogen atom to form a halide ion with
A
2 valence electrons
B
3 valence electrons
C
7 valence electrons
D
8 valence electrons
CORRECT OPTION: d
9
The shape of s-orbitals is
A
spherical
B
elliptical
C
spiral
D
circular
CORRECT OPTION: a
10
22688Ra → x86Rn + α - particle
What is the value of x in the nuclear reaction above?
A
220
B
222
C
226
D
227
CORRECT OPTION: b
22688Ra → 22286Rn + α - particle
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