Electrolytic Refining

Q. Native silver metal forms a water soluble complex with a dilute aqueous solution of NaCN in the presence of
(IIT-JEE, 2008)

1. Oxygen
2. Carbon dioxide
3. Argon
4. Nitrogen

Q.

In the electrolytic refining of Copper (electrolyte is $CuS{O}_4$ solution + dil $H_{2}S{O}_4$ _;Pure Cu cathode and Impure Cu anode), metallic impurities having lower oxidation potential than Cu are deposited as __ sludge.

Q. When copper metal is refined by electrolytic method, incorrect statement is

1. Anode is made of impure metal while pure metal is cathode
2. $CuS{O}_4$ can be used as electrolyte
3. During electrolysis impurities collected as anode mud
4. Anode is made of pure metal while cathode is made of impure metal

Q.

In electrolytic refining, the impure metal acts as anode.

1. True

2. False

Q. Copper is purified by the electrolytic refining of blister copper. The correct statement(s) about this process is/are:

1. impure Cu strip is used as cathode
2. acidified aqueous $CuS{O}_4$is used as electrolyte
3. pure $Cu$ deposits at cathode
4. impurities settle as anode mud

Q. In the electrolytic refining of copper using $CuS{O}_4$ as the electrolyte, the anode reaction is

1. $4O{H}^{-}\left(aq\right)\to O_2\left(g\right)+2H_{2}O\left(l\right)+4e^{-}$
2. $C{u}^{2+}\left(aq\right)+2e^{-}\to Cu\left(s\right)$
3. $2S{O}_4^{2-}\left(aq\right)\to S_2{O}_8^{2-}\left(aq\right)+2e^{-}$
4. $Cu\left(s\right)\to C{u}^{2+}\left(aq\right)+2e^{-}$

Q.

Out line the principles of refining metals by the following method:

Zone refining

Electrolytic refining

Vapour phase refining

Q.

Name the common elements presents in the anode mud in electrolytic refining of copper. Why are they so present?

Q.

During the process of electrolytic refining, the pure metal is deposited at the ________.

1. anode
2. initially at cathode and then at anode
3. cathode
4. bottom of the solution

Q.

Pure gold is equal to

1. 24 carat

2. 10 carat

3. 22 carat

4. 26 carat