In liquation process used for tin (Sn), the metal

We are asked about the liquation process used for refining tin (Sn).

Liquation is a metallurgical purification method that exploits the difference in melting points between a metal and its impurities. Tin has a relatively low melting point of about 232°C, whereas many of its common impurities have much higher melting points.

In this process, the impure tin ore is placed on the top of a sloping surface (hearth) and heated gently. Since tin melts at a lower temperature than its impurities, the tin melts and flows down the slope under gravity, leaving behind the higher-melting-point impurities on the hearth. The molten tin is collected at the bottom in a pure form.

Now let us check the options. Option A (reacted with acid) describes acid leaching, not liquation. Option B (dissolved in water) is irrelevant since metals like tin do not dissolve in water. Option D (fused with NaOH) describes a fusion process for dissolving amphoteric ores, not liquation. Option C correctly states that the metal is brought to molten form and made to flow on a slope, which is precisely what happens in liquation.

Hence, the correct answer is Option C.