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?
Απάντηση
(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
Απάντηση
(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]
Απάντηση
(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
Απάντηση
(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]
Απάντηση
(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
Απάντηση
(C)
neutralization
8
Which of the following processes is an endothermic reaction?
Απάντηση
(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?
Απάντηση
(D)
Action on starch iodide paper
10
The indicator used in neutralizing CH3COOH and NaOH solution has pH range of
Απάντηση
(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.
Απάντηση
(A)
ZnCl2(aq)
12
Which of the following compounds absorbs moisture from the atmosphere and dissolves in it?
Απάντηση
(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?
Απάντηση
(A)
Increase in temperature
14
Electrolysis is applied in the following processes except
Απάντηση
(C)
extraction of iron
15
The oxidation number of iodine in the iodate ion (IO -3) is
Απάντηση
(D)
+5
16
Metals can be extracted from their ores by a process involving
Απάντηση
(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?
Απάντηση
(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?
Απάντηση
(B)
MnO-4
19
Which of the following industrial processes is chlorines not used?
Απάντηση
(C)
Manufacturing of common salt
20
What type of reaction occurs between vegetable oil and plant ash extract?
Απάντηση
(D)
Saponiflication
21
Which of the following compounds is an alkanoate?
Απάντηση
(B)
CH3COOCH3
22
What is CaHb in the following equation? C a
H b + 5O2 → 3CO 2 + 4H2O
Απάντηση
(C)
C3H8
23
Greenhouse effect can be reduced by controlling
Απάντηση
(B)
burning wood and fossil fuel
24
Waste plastics accumulate in the soil and pollute the environment because plastic materials are
Απάντηση
(B)
non -biodegradable
25
Which of the following substance is an ore of iron?
