1993 - JAMB Chemistry Past Questions and Answers - page 3
21
The standard enthalpies of formation of CO2(g), H2O(g) and CO(g) in kJ mol- are -394, -242 and -110 respectively. What is the standard enthalpy change for the reaction CO(g) + H2(g)O → CO2(g) + H2(g)?
A
-42 KJ mol-
B
+42 KJ mol-
C
-262 KJ mol-
D
+262 KJ mol-
correct option: a
Standard enthalpy change of a process = ∆H° process = ∆H° F reactant - DF° products
Users' Answers & Comments22
10g of a solid is in equilibrium with its own vapour.
When 1 g of a small amount of solid is added, the vapour pressure?
When 1 g of a small amount of solid is added, the vapour pressure?
A
remains the same
B
drops
C
increases by 1%
D
increases by 99%
correct option: b
Users' Answers & Comments23
NaCI(s) + H2SO4(I) → HCI(g) + NaHSO4(s).
In the reaction above, H2SO4 behaves as?
In the reaction above, H2SO4 behaves as?
A
a strong acid
B
an oxidizing agent
C
a good solvent
D
a dehydrating agent
correct option: a
Users' Answers & Comments24
Which of these gases can be dried with concentrated H2SO4?
A
HBr
B
H2S
C
NH3
D
SO2
correct option: a
Users' Answers & Comments25
Which of these salts will produce its metal, oxygen and nitrogen (IV) oxide on heating?
A
Silver and trioxonitrate (V)
B
Sodium trioxonitrate (V)
C
Calcium trioxonitrate (V)
D
Lithium trioxonitrate (V)
correct option: a
Users' Answers & Comments26
An experiment produces a gaseous mixtures of carbon (IV) oxide and carbon (II) oxide. In order to obtain pure carbon (II) oxide, the gas mixture should be?
A
passed over heated copper (II) oxide
B
bubbled through concentrated tetraoxosulphate (IV) acid
C
bubbled through sodium hydroxide solution
D
bubbled through water
correct option: c
Users' Answers & Comments27
Which of the following is a property of ionic chlorides?
A
They can be decomposed by heat
B
They react with aqueous AgNO3 to give a white precipiate which is soluble in excess ammonia
C
They explode when in contact with dry ammonia
D
They react with concentrated tetraoxosulphate (IV) acid to give white fumes of chlorine gas
correct option: b
Users' Answers & Comments28
When dilute aqueous solutions of lead (II) nitrate and potassium bromide are mixed, a precipitate is observed.
The products of this reaction are?
The products of this reaction are?
A
PbO(s) + Br- + KNO3
B
Br2 + NO2(g) + PbBr2(s)
C
PbO(s) + K+(aq) + Br(aq) + NO2(g)
D
PbBr2(s) + K(aq) + K+(aq) + NO3(aq)
correct option: d
Users' Answers & Comments29
Bronze is an alloy of?
A
silver and copper
B
silver and gold
C
copper and nickle
D
copper and zinc
correct option: e
Correct Answer: Option E
Bronze is an alloy of copper and tin.
Users' Answers & Comments30
The active reducing agent in the blast furnace for the extraction of iron is?
A
carbon
B
limestone
C
carbon(II)oxide
D
calcium oxide
correct option: c
Users' Answers & Comments