Which metal is generally used for coating of brass utensils to prevent copper contamination?

Which one of the following is called the 'metal of future'?

Which one of the following is essential in corrosion of iron metal?

Which one of the following metals floats in cold water?

To protect steel and iron from rusting, a thin layer of which one of the following metals is applied?

Which one of the following compounds is used to make fireproof clothing?