An element X has isotopic masses of 6 and 7. if the relative abundance is 1 to 12.5 respectively, what is the relative atomic mass of X?
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(C)
6.9
3
An atom 23892X decays by alpha particle emission to give an atom Y. The atomic number and mass number of Y are
Répondre
(A)
90 and 234 respectively
4
If 1 mole of sodium contains 6 x 1023 atoms, how many atoms are contained in 0.6 g of sodium? [Na = 23]
Répondre
(B)
1.56 x 1022
5
If 20 cm3 of distilled water is added to 80cm 3 of 0. 50 mol dm-3 hydrochloric acid, the new concentration of the acid will be
Répondre
(C)
0.40mol dm-3
6
Consider the reaction represented by the equation. 2NaHCO3(s) \(\rightarrow\) 2Na2CO 3(S) + CO 2(g) + H2O(g) what volume of carbon (IV)oxide at s.t.p is evolved when 0. 5 moles of NaHCO3 is heated? [Molar volume = 22.4 dm3 at s.t. p]
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(C)
5.6dm3
7
Considered the reaction: H+(aq) + OH -(aq) → H2O (l). The energy change taking place in the reaction above is enthalpy of
Répondre
(C)
neutralization
8
Which of the following processes is an endothermic reaction?
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(A)
Dissolving NH4CI crystals in water
9
Which of the following aqueous methods cannot be used to distinguish between a strong acid and a a weak acid?
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(D)
Action on starch iodide paper
10
The indicator used in neutralizing CH3COOH and NaOH solution has pH range of
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(C)
8-103
11
When aqueous ammonia is added to one of the following solutions,a white precipitate which dissolved in excess ammonia is formed Identify the solution.
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(A)
ZnCl2(aq)
12
Which of the following compounds absorbs moisture from the atmosphere and dissolves in it?
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(A)
FeCI3
13
Consider the reaction represented by the equation: 2SO\(_{2(g)}\) + O\(_{2(g)}\) ⇌ 2SO\(_{3(g)}\); ∆H = - 197 kJmol\(^{-1}\). Which of the following conditions will not increase the yield of sulphur (VI) oxide?
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(A)
Increase in temperature
14
Electrolysis is applied in the following processes except
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(C)
extraction of iron
15
The oxidation number of iodine in the iodate ion (IO -3) is
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(D)
+5
16
Metals can be extracted from their ores by a process involving
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(A)
reduction
17
Consider the reaction: 2AI(s) + 6H+(aq) → 2AI3+(aq) + 3H2(g). What is the total number of moles of electrons transferred from the aluminium atoms to the hydrogen ions?
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(D)
6
18
In the reaction represented by the equation. 5Fe 2+(aq) + MnO-4(aq) + 8H+(aq) → 5Fe3+(aq) + Mn2+(aq) + 4H2O(l) which species is reduced?
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(B)
MnO-4
19
Which of the following industrial processes is chlorines not used?
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(C)
Manufacturing of common salt
20
What type of reaction occurs between vegetable oil and plant ash extract?
Répondre
(D)
Saponiflication
21
Which of the following compounds is an alkanoate?
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(B)
CH3COOCH3
22
What is CaHb in the following equation? C a
H b + 5O2 → 3CO 2 + 4H2O
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(C)
C3H8
23
Greenhouse effect can be reduced by controlling
Répondre
(B)
burning wood and fossil fuel
24
Waste plastics accumulate in the soil and pollute the environment because plastic materials are
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(B)
non -biodegradable
25
Which of the following substance is an ore of iron?
