1992 - JAMB Chemistry Past Questions and Answers - page 1
1
There is a large temperature interval between the melting point and the boiling point of a metal because?
A
metals have very high melting points
B
metals conduct heat very repaidly
C
melting does not break the metalic bond but boiling does
D
the crystal lattice of metals is easily broken
correct option: a
Users' Answers & Comments2
How many moles of (H+) are there in 1 dm3 of 0.5 M solution of H2SO4?
A
2.0 moles
B
1.0 moles
C
0.5 mole
D
0.25 mole
correct option: b
mole = (M x V ) / (1000cm3) = (0.5 x 1000cm3) = 0.5 moles
For H2SO4 → 2H+SO42-
1 mole of H+ = 0.5 moles
2H+ = 2 x 0.5 mole = 1.0 mole
Users' Answers & CommentsFor H2SO4 → 2H+SO42-
1 mole of H+ = 0.5 moles
2H+ = 2 x 0.5 mole = 1.0 mole
3
wH2SO4 + xAI(OH)3 → yH2O + = zAI2(SO4)3. The respective values of w.x.y and z in the equation above are?
A
2,2,5 and 1
B
3,2,5 and 2
C
3,2,6 and 1
D
2,2,6 and 2
correct option: c
Users' Answers & Comments4
A given mass of gas occupies 2 dm3 at 300k. At what temperature will its volume be doubled keeping the pressure constant?
A
400 k
B
480 k
C
550 k
D
600 k
correct option: d
Users' Answers & Comments5
Which of the following is a measure of the average kinetic energy of the molecules of a substance?
A
Volume
B
Mass
C
pressure from age grades
D
Temperature
correct option: d
Users' Answers & Comments6
If 100 cm3 of oxygen pass through a porous plug in 50 seconds, the time taken for the same volume of hydrogen to pass through the same porous plug is?
(O = 16, H = 1)
(O = 16, H = 1)
A
10.0 s
B
12.5 s
C
17.7 s
D
32.0 s
correct option: b
100 cm3 of O2 diffuse 50 sec
∴ 100 cm3 of H2 → (100) / (100) x (50) /(1)
t1 50 sec
molecular mass H+ → 2 x 1 = 2
molecular mass of O2 16 x 2 = 32
T2 = t1 √M2/M1 = t2 = 50 √2/32
50√0.625 = 50 x 0.25 = 12.5 secs
Users' Answers & Comments∴ 100 cm3 of H2 → (100) / (100) x (50) /(1)
t1 50 sec
molecular mass H+ → 2 x 1 = 2
molecular mass of O2 16 x 2 = 32
T2 = t1 √M2/M1 = t2 = 50 √2/32
50√0.625 = 50 x 0.25 = 12.5 secs
7
An increase in temperature causes an increase in pressure of a gas in a fixed volume due to an increase in the?
A
number of molecules of the gas
B
density of the gas molecules
C
number of collisions between the gas molecules
D
number of collisions between the gas molecules and the walls of the container
correct option: d
Users' Answers & Comments8
The nucleus of the isotope tritium, contains?
A
two neutrons with no protons
B
one neutron and one protons
C
two neutrons and one proton
D
two neutrons, one proton and one electron
correct option: c
Users' Answers & Comments9
How many lone pairs of electron are there on the central atom of the H2O molecules?
A
1
B
2
C
3
D
4
correct option: a
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The electron-dot structure of NH 3 places one pair of non-bonding electrons in the valence shell of the nitrogen atom. This means that there are three bonded atoms and one lone pair for a coordination number of four around the nitrogen, the same as occurs in H 2O.
Users' Answers & CommentsThe electron-dot structure of NH 3 places one pair of non-bonding electrons in the valence shell of the nitrogen atom. This means that there are three bonded atoms and one lone pair for a coordination number of four around the nitrogen, the same as occurs in H 2O.
10
147N + X → 178O + 11 H. In the above reaction, X is a?
A
neutron
B
helium atom
C
litgium atom
D
deuterium atom
correct option: b
Users' Answers & Comments