Question

Copper and brass utensils are tinned

Answer 1

Homogeneous mixtures of any number of metals are called Alloys. Alloys are highly resistant to corrosion,i.e,do not get tarnished or damaged when kept in open air whereas pure metals like copper are vulnerable to atmospheric oxidation and consequently corrosion. 
Copper and Tin form an alloy called Brass and Copper and Zinc form Bronze alloy. So, it is copper metal which gets coated by a highly corrosion resistant metal like Tin to protect it from reacting with the oxygen and water vapor of air to form undesirable rust and copper gets protected in this way from any natural damage

Answer 2

Copper and brass vessels are subject to chemical action caused by sour or acid food placed in them. This action is lessened, if not prevented, by the tin-coating applied to the vessels. Persons who have made tin-coating a profession are called 'Kalhaiwallas'.


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