Which of the following reactions represents the laboratory preparation of hydrogen?
Απάντηση
(C)
Zn(s) + 2HCI(aq) → ZnCI2(aq) + H2(g)
3
Which of the following statements best explains cracking ? It is a process
Απάντηση
(B)
in which large hydrocarbon molecules are broken into smaller units
4
120cm3 of hydrogen were sparked with 60cm 3 of oxygen at 110oC. What was the volume of stream produced? The equation for the reaction is 2H2(g) + O2(g) → 2H2O(g)
Απάντηση
(D)
120cm3
5
The earthly impurities in iron ore are removed in the blast furnace by the reaction
Απάντηση
(C)
SiO2 + CaO →CaSiO3
6
Which of the following hydrocarbons is not likely to be present in petrol?
Απάντηση
(A)
C14H30
7
The most suitable method to use when separating an insoluble solid from a liquid is
Απάντηση
(B)
filtration
8
The following are miscible with water except
Απάντηση
(A)
ethylethanoate
9
If 200cm 3 of a gas at s.t.p. has a mass of 0.268g, what is its molar mass? (Molar volume of a gas at s.t.p. = 22.4 dm3)
Απάντηση
(D)
30g
10
How many carbon atoms are there in a benzene ring?
Απάντηση
(C)
6
11
Which of the following gases will bleach moist litmus paper?
Απάντηση
(A)
CI2
12
Given that for the reaction KOH (aq) + HCI(aq) → KCI(aq) + H2O(L) H = - 54 Kj mol-1. What is the quantity of heat involved in the reaction?2NaOH(aq) + H2SO 4(aq) → Na2SO4(aq) + 2H 2O(l)?
Απάντηση
(A)
- 108Kj
13
When an element can exist in two or more forms in the same physical state, the element is said to exhibit
Απάντηση
(C)
allotropy
14
Which of the following carbohydrates does NOT usually occur in the crystalline form?
Απάντηση
(E)
Cellulose
15
Copper can best be purified by
Απάντηση
(C)
electrolyzing a copper (ll) salt solution using the impure copper as the anode
16
Locally produced soap in which wood ash is used as the base is usually soft because the wood ash contains a lot of
Απάντηση
(B)
potassium ions
17
Why is potassium fluoride added to the electrolyte in the extraction of sodium from fused sodium chloride?
Απάντηση
(D)
Potassium fluride reduces the temperature at which sodium chloride fuses
18
The rate of the hydrogen in the reaction Zn(s) + 2HCI (aq) → ZnCI 2(g) + H 2(aq) + H 2(g) can be increased by
Απάντηση
(A)
using Zinc powder instead of Zinc granules
19
Octane number is highest in petrol containing a high proportion of
Απάντηση
(E)
2,2,4-trimethylpentane
20
Given the following half-cell reaction; 2Cl(aq) → CI2(g) + 2e, how many mole of electrons will be required to produce 1.12dm3 of chlorine gas at s.t.p? (Molar volume of a gas at s.t.p. = 22.4dm 3)
Απάντηση
(D)
0.10
21
Which of the following is used extensively in manufacturing photographic chemicals?
Απάντηση
(C)
Silver chloride
22
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)
Απάντηση
(B)
1 x 6.02 x10 23
23
If sulphur is dissolved in carbon (IV) sulphide and the solution allowed to evaporate the allotrope of sulphur formed is
Απάντηση
(C)
rhombic sulphur
24
If sulphur is dissolved in carbon (IV) sulphide and the solution is allowed to evaporate, the allotrope of sulphur formed is
Απάντηση
(C)
rhombic sulphur
25
Given that for the reaction. N2(g) + 3H2(g) ⇌ 2NH3(g) ∆H = -92kJ. What is the enthalpy of formation of ammonia from its elements?
Απάντηση
(A)
-46KJ mol -1
26
The following are s-block elements except
Απάντηση
(E)
aluminium
27
Which of the following statements is not true of tin? it
Απάντηση
(D)
combines with copper to form the alloy brass
28
What quantity of copper will be deposited by the same quantity of electricity that deposited 9.0g of aluminum? (A = 27, Cu = 64)
Απάντηση
(B)
32g
29
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?
Απάντηση
(B)
x belongs to group 1, Y belongs to period 4
30
Which of the following is a condition for a spontaneous reaction?
