No explanation is given for this question. Let's discuss the answer together.
53.
During a column chromatography through $$A{l_2}{O_3}$$ column, a mixture of components $$A, B$$ and $$C$$ is passed through the column. On adding eluant, compound $$'A'$$ is eluted first then $$'B'$$ and in the end $$'C'.$$ Which of the following statements regarding the components is correct?
A
The order of adsorption of $$A, B$$ and $$C$$ is $$C>B>A.$$
B
The order of adsorption of $$A, B$$ and $$C$$ is $$A > B > C.$$
C
The order of adsorption of $$A, B$$ and $$C$$ is $$B > A > C.$$
D
The order of adsorption of $$A, B$$ and $$C$$ is $$B > C > A.$$
Answer :
The order of adsorption of $$A, B$$ and $$C$$ is $$C>B>A.$$
Since compound $$'A'$$ comes out before $$'B', 'B'$$ is more
readily adsorbed to the column and $$'B'$$ comes out before $$'C',$$ hence $$'C'$$ is more readily adsorbed than $$'B'.$$ Hence, the order of adsorption is $$C > B > A.$$
54.
Mark the correct statements.
(i) Mercury can be refined by the process of distillation.
(ii) In poling, the molten impure metal is stirred with green poles of wood.
(iii) In electrolytic refining of metals, impure metal is made as cathode and a thin strip of pure metal is made as anode.
In electrolytic refining of metals, impure metal is made as anode and a thin strip of pure metal is made as cathode.
55.
Roasting of copper pyrite ores is for the following purpose
A
to burn off sulphur, arsenic, antimony etc. as oxides and convert all the iron and copper to their oxides
B
to burn off arsenic, antimonyetc. as oxides and burn off sulphur so that enough of it remains to combine with all the copper
C
to burn off sulphur partially, in order to leave enough of sulphur to combine with arsenic antimony etc. and to convert all the iron and copper to oxides
D
to melt arsenic and antimony sulphides etc. and remove them by liquation and to burn off sulphur partially to leave enough to combine with copper and iron
Answer :
to burn off sulphur partially, in order to leave enough of sulphur to combine with arsenic antimony etc. and to convert all the iron and copper to oxides
No explanation is given for this question. Let's discuss the answer together.
56.
Which of the following statements is correct according to the basic concepts of thermodynamics which govern the feasibility of a metallurgical process?
A
When the value of $$\Delta G$$ is positive for the equation $$\Delta G = \Delta H - T\Delta S,$$ the reaction will proceed.
B
If reactants and products of two reactions are put together and net $$\Delta G$$ is $$-ve,$$ the overall reaction will occur.
C
On increasing the temperature, the value of $$\Delta G$$ becomes $$+ve.$$
D
Feasibility of thermal oxidation of an ore can be established by Ellingham diagram in which a straight line shows the reduction reaction will proceed.
Answer :
If reactants and products of two reactions are put together and net $$\Delta G$$ is $$-ve,$$ the overall reaction will occur.