Q. No.The role of depressant in froth floatation process is :
| 1. | To separate two nitrite ores by selectively preventing one ore from forming froth. |
| 2. | To separate two sulphide ores by selectively preventing one ore from forming froth. |
| 3. | To separate two sulphide ores by selectively preventing both of them from forming froth. |
| 4. | To separate two magnesium ores by selectively preventing both of them from forming froth. |
Leaching of low-grade copper ores does not involve
1. Cu getting converted into Cu2+(aq) in acidic medium
2. Cu getting converted into Cu2+(aq) in basic medium
3. Cu2+(aq) getting reduced to Cu
4. using bacteria in the presence of air.
Incorrect statement(s) among the following options is/are:
| 1. | Roasting is done in a limited supply of air. |
| 2. | Calcination is done in the absence, or a limited supply of air. |
| 3. | Roasting is done in a regular supply of air. |
| 4. | All of the above. |
The extraction of copper from pyrites is more difficult than from its oxide ores through reduction because -
1. of HCl is less than that of
2. of HNO3 is less than that of
3. of is less than that of
4. of CuSO4 is less than that of
‘Cast iron’ is different from ‘Pig iron' because :
| 1. | Cast iron is obtained by melting pig iron and coke using a hot air blast. |
| 2. | Cast iron contains lower amount of carbon (3%) than pig iron. |
| 3. | Unlike pig iron, cast iron is extremely hard and brittle. |
| 4. | All of the above |
Zinc cannot be extracted from zinc oxide via CO reduction because:
(Given: Ellingham diagram)
| 1. | \(\Delta G_{f}^{o} \) of Zn from ZnO is lower than that of CO2 from CO |
| 2. | \(\Delta G_{f}^{o} \) of ZnO from Zn is lower than that of CO2 from CO |
| 3. | ZnO is less stable than CO |
| 4. | ZnO is more stable than CO |
The chemical reactions taking place in the extraction of zinc from zinc blende is
1.
2.
3. Both 1 and 2
4. None of the above
The role of silica in the metallurgy of copper is :
| 1. | To remove the iron oxide obtained during the process of roasting as ‘slag’. |
| 2. | To remove the sulphur oxide obtained during the process of roasting as ‘slag’. |
| 3. | To remove the nitrogen oxide obtained during the process of roasting as ‘slag’. |
| 4. | To remove the aluminium oxide obtained during the process of roasting as ‘slag’. |
The correct statement among the following is:
| 1. | All ores are minerals, but all minerals are not necessarily ores. |
| 2. | Minerals are an economical source of metal |
| 3. | Extraction of metal from ores is difficult. |
| 4. | None of the above |
The value of âfGO for the formation of is – 540 kJmol−1and that of Al2O3 is – 827 kJ mol−1. The correct statement is-
1. Cr can reduce Al2O3 to Al
2. Cr2O3 cannot reduce Al2O3 to Al
3. Al can reduce to Cr
4. Al cannot reduce to Cr
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