2008 - JAMB Chemistry Past Questions and Answers - page 1
1
Chlorophyll obtained from given leaves of plant can be shown to be composed of more than one coloured component by the technique of
A
crystallization
B
hydrolysis
C
chromatography
D
sublimation
correct option: c
Users' Answers & Comments2
In countries where the temperature falls below 273K, salt is always sprinkled on the icy road in order to
A
lower the melting point of the ice
B
increase the density of the ice
C
make the ice impure
D
raise the melting point of the ice
correct option: a
Users' Answers & Comments3
2Na(s) + 2H2O(l) → 2NaOH(aq) + H2(g)
From the equation above, calculate the mass of sodium hydroxide produced by 2.3g of sodium.
[H = 1, O = 16, Na = 23]
From the equation above, calculate the mass of sodium hydroxide produced by 2.3g of sodium.
[H = 1, O = 16, Na = 23]
A
0.40g
B
0.80g
C
4.00g
D
8.00g
correct option: c
2Na(s) + 2H2O(l) → 2NaOH(aq) + H2(g)
Relative molecular mass of NaOH = 23 + 16 + 1 = 40smol-1
2 * 23g of sodium react with water to produce
2 * 40g of NaOH
∴ 2.3g of sodium will react with water to produce
(2.3 * 40 * 2)/(23 * 2) = 4.00g
Users' Answers & CommentsRelative molecular mass of NaOH = 23 + 16 + 1 = 40smol-1
2 * 23g of sodium react with water to produce
2 * 40g of NaOH
∴ 2.3g of sodium will react with water to produce
(2.3 * 40 * 2)/(23 * 2) = 4.00g
4
16.8 g of sodium hydrogen trioxocarbonate (IV) is completely decomposed by heat. Calculate the volume of carbon(IV) oxide given off s.t.p
[Na 23, C = 12, O = 16, H = 1, Molar volume of a gas at s.t.p = 22.4 dm3]
[Na 23, C = 12, O = 16, H = 1, Molar volume of a gas at s.t.p = 22.4 dm3]
A
22.40 dm3
B
11.20 dm3
C
2.24 dm3
D
1.12 dm3
correct option: c
2NaHCO3(s) → Na2CO3(s) + H2O(l) + CO2
Relative molecular mass of NaHCO3 = 23 +1 + 12 + 16 * 3 = 84smol-1
2 * 84g of NaHCO3 will be liberated 22.4dm3 or CO2 at s.t.p
16.8g of NaHCO3 will libertae (16.8 * 22.4)/(2 * 84) = 2.24 dm3
Users' Answers & CommentsRelative molecular mass of NaHCO3 = 23 +1 + 12 + 16 * 3 = 84smol-1
2 * 84g of NaHCO3 will be liberated 22.4dm3 or CO2 at s.t.p
16.8g of NaHCO3 will libertae (16.8 * 22.4)/(2 * 84) = 2.24 dm3
5
300 cm3 of gas has a pressure of 800 mmHg. If the pressure is reduced to 650 mmHg, find its volume
A
243.75 cm3
B
369.23 cm3
C
738.46 cm3
D
1733.36 cm3
correct option: b
P1V1= P2V2
800 * 300 = 650 * V2
V2 = (800 * 300)/650 = 369.23 cm3
Users' Answers & Comments800 * 300 = 650 * V2
V2 = (800 * 300)/650 = 369.23 cm3
6
Diffusion is slowest in solid particles than in particles of liquid and gases because
A
solid particles have more kinetic energy than the particles of liquid and gases
B
solid particles have less kinetic energy than the particles of liqiud and gases
C
solid particles have less restriction in their movement than liquid and gas particles
D
the particles in solids are far apart and the cohesive forces between them are negligible
correct option: b
Users' Answers & Comments7
The experiment that showed that atoms have tiny positively charged nucleus was first carried out by
A
Moseley
B
Rutherford
C
Millikan
D
Dalton
correct option: b
Users' Answers & Comments8
The atom of an element X is represented as zyX. The basic chemical properties of X depends on the value of
A
Y
B
Z
C
Y - Z
D
Z - Y
correct option: b
Users' Answers & Comments9
A
carbon
B
nitrogen
C
oxygen
D
flourine
correct option: c
Users' Answers & Comments10
In the periodic table, the electrical and thermal conductivities are properties of elements that
A
decrease across the period and increase down the group
B
increase across the period and decrease down the group
C
decrease across the period and down the group`
D
increase acrosss the period and down the group
correct option: a
Users' Answers & Comments