171. Removal of the unwanted materials like sand, clay, etc. from the ore is known as _________, _________ or _________.
A
concentration, dressing, benefaction
B
separation, refining, gangue
C
magnetic separation, purification, gangue
D
washing, refining, amalgamation
Answer :
concentration, dressing, benefaction
172. Extraction of chlorine from brine is based on
A
reduction
B
displacement
C
oxidation
D
evaporation
Answer :
oxidation
173. Which of the following metal evolves hydrogen on reacting with cold dilute $$HN{O_3}?$$
A
$$Mg$$
B
$$Al$$
C
$$Fe$$
D
$$Cu$$
Answer :
$$Mg$$
174.
Column chromatography involves separation of a mixture over a column of adsorbent ( stationary phase ) packed in a glass tube. Depending upon the degree of adsorption complete separation takes place. In the given column, three coloured bands $$x,y,z$$ are formed. Identify the correct statement.
A
$$x, y$$ and $$z$$ are adsorbed to the same extent.
B
The most readily adsorbed component is retained near the top $$\left( x \right).$$
C
The most readily adsorbed component comes down $$\left( z \right).$$
D
$$x, y, z$$ layers are formed according to the wavelengths of the colours not on the basis of adsorption.
Answer :
The most readily adsorbed component is retained near the top $$\left( x \right).$$
175. Which of the following elements is present as the impurity to the maximum extent in the pig iron?
A
Manganese
B
Carbon
C
Silicon
D
Phosphorus
Answer :
Carbon
176. Which of the following statements regarding electrolytic refining of copper is incorrect ?
A
In this process anode is made up of impure copper and pure copper strips are taken as cathode.
B
Acidic or basic solution of copper sulphate is used as electrolyte
C
Antimony, tellurium, silver and gold are some of the metals deposits as anode mud during this process
D
Zinc can be also refined by electrolytic refining method.
Answer :
Acidic or basic solution of copper sulphate is used as electrolyte
177. In the metallurgy of aluminium
A
$$A{l^{3 + }}$$ is oxidised to $$A{l_{\left( s \right)}}$$
B
graphite anode is oxidised to carbon monoxide and carbon dioxide
C
oxidation state of oxygen changes in the reaction at anode
D
oxidation state of oxygen changes in the overall reaction involved in the process
Answer :
graphite anode is oxidised to carbon monoxide and carbon dioxide
178. Which one of the following is true in electrolytic refining?
A
Impure metal is made cathode.
B
Impure metal is made anode.
C
Impure metal is made cathode and pure metal as anode.
D
Both electrodes must be of pure metal.
Answer :
Impure metal is made anode.
179.
During the formation of the slag by the reaction of flux and impurities which of the following is an example of acidic and basic flux?
$$\eqalign{
& \left( {\text{i}} \right)FeO + Si{O_2} \to FeSi{O_3} \cr
& \left( {{\text{ii}}} \right)Si{O_2} + MgO \to MgSi{O_3} \cr} $$
A
(i) $$Si{O_2} $$ - Acidic flux (ii) $$MgO $$ - Basic flux
B
(i) $$Si{O_2} $$ - Basic flux (ii) $$MgO$$ - Acidic flux
C
(i) $$Si{O_2} $$ - Basic flux (ii) $$MgO $$ - Basic flux
D
(i) $$Si{O_2} $$ - Acidic flux (ii) $$MgO $$ - Acidic flux
Answer :
(i) $$Si{O_2} $$ - Acidic flux (ii) $$MgO $$ - Basic flux
180. In electrorefining of copper some gold is deposited as
A
anode mud
B
cathode mud
C
electrolyte
D
None of these
Answer :
anode mud