Ores and Metallurgy MCQ Questions & Answers in Inorganic Chemistry | Chemistry
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211.
Galena is an ore of
A
$$Pb$$
B
$$Hg$$
C
$$Zn$$
D
$$Cu$$
Answer :
$$Pb$$
Galena is an ore of lead. It is $$PbS.$$
212.
Match the column I with column II and mark the appropriate choice.
Column I
Column II
a.
Calcination
1.
$$C{r_2}{O_3} + 2Al \to 2Cr + A{l_2}{O_3}$$
b.
Roasting
2.
$$FeC{O_3} \to FeO + C{O_2}$$
c.
Smelting
3.
$$2ZnS + 3{O_2} \to 2ZnO + 2S{O_2}$$
d.
Aluminothermy
4.
$$PbO + C \to Pb + CO$$
A
a - 1, b - 2, c - 3, d - 4
B
a - 4, b - 3, c - 2, d - 1
C
a - 3, b - 2, c - 1, d - 4
D
a - 2, b - 3, c - 4, d - 1
Answer :
a - 2, b - 3, c - 4, d - 1
No explanation is given for this question. Let's discuss the answer together.
213.
Aluminothermic process is used for the extraction of metals, whose oxides are
A
fusible
B
not easily reduced by carbon
C
not easily reduced by hydrogen
D
strongly basic.
Answer :
not easily reduced by carbon
When reduction by carbon is not satisfactory in case of metals having high $$m.pt.,$$ aluminothermic process is used.
214.
The value of $${\Delta _f}{G^ \circ }$$ for formation of $$C{r_2}{O_3}$$ is $$ - 540\,kJmo{l^{ - 1}}$$ and that of $$A{l_2}{O_3}$$ is $$ - 827\,kJ\,mo{l^{ - 1}}$$ What is the value of $${\Delta _r}{G^ \circ }$$ for the reaction ?
$$\frac{4}{3}Al\left( s \right) + \frac{2}{3}C{r_2}{O_3}\left( s \right) \to \frac{2}{3}A{l_2}{O_3}\left( s \right) + \frac{4}{3}Cr\left( s \right).$$
A
$$ - 574\,kJ\,mo{l^{ - 1}}$$
B
$$ - 287kJ\,mo{l^{ - 1}}$$
C
$$ + 574\,kJ\,mo{l^{ - 1}}$$
D
$$ + 287kJ\,mo{l^{ - 1}}$$
Answer :
$$ - 287kJ\,mo{l^{ - 1}}$$
$$\eqalign{
& {\text{The two equation are :}} \cr
& \frac{4}{3}Al\left( s \right) + {O_2}\left( g \right) \to \frac{2}{3}A{l_2}{O_3}\left( s \right), \cr
& {\Delta _f}{G^ \circ } = - 827kJ\,mo{l^{ - 1}}\,\,\,...\left( 1 \right) \cr
& \frac{4}{3}Cr\left( s \right) + {O_2}\left( g \right) \to \frac{2}{3}C{r_2}{O_3}\left( s \right), \cr
& {\Delta _f}{G^ \circ } = - 540kJ\,mo{l^{ - 1}}\,\,\,...\left( 2 \right) \cr} $$
Subtracting equation (ii) from equation (i)
$${\text{we have,}}$$
$$\frac{4}{3}Al\left( s \right) + \frac{2}{3}C{r_2}{O_3}\left( s \right),$$ $$ \to \frac{2}{3}A{l_2}{O_3}\left( s \right) + \frac{4}{3}Cr\left( s \right),$$
$${\Delta _r}{G^ \circ } = - 287kJ\,mo{l^{ - 1}}$$
215.
A coupled reaction takes place as follow –
$$\eqalign{
& A + B \to C + D\,\,\,\,\Delta {G^ \circ } = + x\,kj \cr
& D + E \to F\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\Delta {G^ \circ } = - y\,kj \cr} $$
for the spontaneity of reaction
$$A + B + E \to C + F,$$ which of the following is correct?
A
$$2x = y$$
B
$$x < y$$
C
$$x > y$$
D
$$x = \left( y \right) \times T\Delta S$$
Answer :
$$x < y$$
For a spontaneous reaction , $$\Delta {G^ \circ }$$ must be negative and it can be possible only in this case when $$x < y$$
216.
During the extraction of haematite, limestone is added which acts as
A
flux
B
slag
C
reducing agent
D
gangue
Answer :
flux
$$CaC{O_3}$$ is added as flux. It decomposes to give $$CaO$$ which reacts with $$Si{O_2}$$ to form slag.
$$\eqalign{
& CaC{O_3} \to CaO + C{O_2} \cr
& \mathop {CaO}\limits_{{\text{Flux}}} + \mathop {Si{O_2}}\limits_{{\text{Gangue}}} \to \mathop {CaSi{O_3}}\limits_{{\text{Slag}}} \cr} $$
217.
Calamine is an ore of :
A
zinc
B
aluminium
C
iron
D
copper
Answer :
zinc
$$ZnC{O_3} = {\text{calamine}}{\text{.}}$$
218.
How do we separate two sulphide ores by froth floatation method?
A
By using excess of pine oil
B
By adjusting proportion of oil to water or using depressant
C
By using collectors and froth stabilisers like xanthates
D
By using some solvent in which one of the sulphides is soluble
Answer :
By adjusting proportion of oil to water or using depressant
By using depressants or adjusting proportion of oil to water, selective prevention of one sulphide ore from coming to the froth is possible.
219.
Which one of the following is not a sulphide ore ?
A
Magnetite
B
Iron pyrites
C
Copper glance
D
Sphalerite
Answer :
Magnetite
The formula of magnetite is $$F{e_3}{O_4}.$$
220.
Which of the following reactions is not taking place in Blast furnace during metallurgy of iron between the temperature range of $$500 - 800\,K?$$