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
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(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]
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(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
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(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
Одговорити
(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
Одговорити
(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?
Одговорити
(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?
Одговорити
(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
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(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?
