1989 - WAEC Chemistry Past Questions and Answers - page 3
21
Which of the following is used extensively in manufacturing photographic chemicals?
A
Aluminium chloride
B
Zinc chloride
C
Silver chloride
D
Mercury (ll) chloride
correct option: c
Users' Answers & Comments22
Given that 1 mole of carbon -12 weighs 12.0g, how many atoms are there in 24.0g magnesium? (C = 12, Mg = 24, NA = 6.02 x 10 23mol-1)
A
1/2 x 6.02 x 10 23
B
1 x 6.02 x10 23
C
2 x 6.02 x 10 23
D
3x 6.02 x 10 23
correct option: b
Users' Answers & Comments23
What is the concentration, in mol dm 3, of solution is allowed to evaporate the allotrope of sulphur formed is
A
plastic sulphur
B
amorphous sulphur
C
rhombic sulphur
D
monoclinc sulphur
correct option: c
Users' Answers & Comments24
If sulphur is dissolved in carbon (IV) sulphide and the solution is allowed to evaporate, the allotrope of sulphur formed is
A
plastic sulphur
B
amorphous sulphur
C
rhombic sulphur
D
monoclinc sulphur
correct option: c
Users' Answers & Comments25
Given that for the reaction. N2(g) + 3H2(g) ⇌ 2NH3(g) ∆H = -92kJ. What is the enthalpy of formation of ammonia from its elements?
A
-46KJ mol -1
B
-184KJmol -1
C
-92KJmol -1
D
184KJmol -1
correct option: a
In the reaction the enthalpy of formation 2 mole of NH3 is - 92kJ. Therefore the standard \(\Delta H\) of formation = \(\frac{-92kJ}{2} = -46KJmol^{-1}\).
26
The following are s-block elements except
A
lithium
B
magnesium
C
potassium
D
calcium
correct option: e
Users' Answers & Comments27
Which of the following statements is not true of tin? it
A
is a p-block element
B
is extracted from cassiterite SnO 2
C
is used for protecting iron containers from corrosion
D
combines with copper to form the alloy brass
correct option: d
Users' Answers & Comments28
What quantity of copper will be deposited by the same quantity of electricity that deposited 9.0g of aluminum? (A = 27, Cu = 64)
A
64g
B
32g
C
7.1g
D
6.4g
correct option: b
Users' Answers & Comments29
The electronic configuration of two atoms X and Y are as follows: X - 1s 2 2s 22p 63s 1, Y -1s 22s 22p 63s23p 64s 2 which of the statements below is true of the position of X and Y in the Periodic Table?
A
x belongs to group 1, Y belongs to period 2,
B
x belongs to group 1, Y belongs to period 4
C
x belongs to group 2, Y belongs to period 1
D
x belongs to group 3, Y belongs to period 2
correct option: b
Users' Answers & Comments30
Which of the following is a condition for a spontaneous reaction?
A
∆H -T is zero
B
∆H-T∆ S is positive
C
∆H-T∆ S is negative
D
∆S is zero
correct option: c
Users' Answers & Comments