General Principles and Processes of Isolation of Elements  MCQs

MCQs of General Principles and Processes of Isolation of Elements

Showing 21 to 30 out of 154 Questions
21.
State the negative silicate ion in an aluminium mineral called kaolinite.
(a) Si2 O52-
(b) Si4 O116-
(c) Si3 O96-
(d) Si O44-
Answer:

Option (a)

22.
Which of the following is not a method of concentration of ores ?
(a) Froth floatation
(b) Calcination
(c) Leaching
(d) Hydraulic washing
Answer:

Option (b)

23.
Which depressant is added to the ore containing ZnS and PbS ?
(a) Cu2(CN)2
(b) KCN
(c) HCN
(d) NaCN
Answer:

Option (d)

24.
Mention the reaction representing example of leaching.
(a) 3Fe2O3 + CO → 2Fe3O4 + CO2
(b) 2Cu2S + 3O2 → 2Cu2O + 2SO2
(c) 4M + 8CN- + 2H2O + O2 → 4 [M(CN)2]- + 4OH-
(d) ZnCO3 ZnO(s) + CO2(g)
Answer:

Option (c)

25.
When impure (native) silver is reacted with dilute aqueous solution of NaCN to form a water soluble complex, whose presence is necessary ?
(a) N2
(b) O2
(c) CO2
(d) Ar
Answer:

Option (b)

26.
Before extracting metal from its sulphide ore, it is converted into its oxide. The ore is not reduced directly by carbon. Why ?
(a) Metal sulphide is thermodynamically more stable that CS2
(b) Carbon dioxide is thermodynamically more stable that CS2
(c) Metal sulphides are less stable than their corresponding oxides.
(d) CO2 is more volatile than CS2
Answer:

Option (c)

27.
What are the values of x and y for the reaction xCu2S(s) + yO2(g)xCu2O(s) + xSO2(g) ?
(a) x = 2, y = 2
(b) x = 3, y = 2
(c) x = 2, y = 3
(d) x = 3, y = 3
Answer:

Option (c)

28.
Use of electrolysis is not done in _____ .
(a) production of KOH
(b) purification of metals
(c) production of water
(d) production of Na
Answer:

Option (c)

29.
What is the value of ΔG° for oxidation-reduction reactions ?
(a) < 0
(b) > 0
(c) = 0
(d) ≤ 0
Answer:

Option (a)

30.
How is Gibbs-Helmholtz equation expressed ?
(a) ΔH = ΔG - TΔS
(b) S=H+GT
(c) ΔG = ΔH - TΔS
(d) ΔG = ΔH + TΔS
Answer:

Option (c)

Showing 21 to 30 out of 154 Questions