Question

Assertion: Lead, tin and bismuth are purified by liquation method.
Reason: Lead, tin and bismuth have low m.p as compared to impurities.
A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion.
B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion.
C. Assertion is correct and Reason is incorrect.

Answer 1

Liquation can be defined as a process employed in metallurgy for the separation of metals from their alloy or ore. The metal-impurity mixture must be heated strongly such that the metal melts and gets converted into its liquid form and flows away under the application of gravity and gets separated from the impurities.

Complete answer:
In liquation process, a mixture of impurities such as oxides of non-metals and unwanted substances along with the desired metal present in it is heated at high temperatures such that the low melting point substance gets converted into its liquid state and flow downwards under the influence of gravity, leaving behind the high melting substances. The melting point of impurities is greater than the melting point of metals. Thus, the substance that attains its melting points early, i.e. metal, will flow away to the next container placed below the heating chamber and thus, the pure metal is collected, leaving behind all the impurities in the heating chamber. The metals that melt at low temperatures include lead ($Pb$), tin ($Sn$ ) and bismuth ($Bi$). Thus, these metals can be purified by liquation method.

Thus, the correct option is A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion.

Note:
The liquation process is not $100\%$ efficient and there is a loss of pure metal as some of the metals fuse together with the impurities and the impurities get dissolved in the molten metal.