Which alloy is used to make surgical instruments?

In the refining of silver,the recovery of silver from silver nitrate solution involves displacement by copper metal. Write down the reaction involved.

Iqbal treated a lustrous,divalent element $M$ with sodium hydroxide. He observed the formation of bubbles in the reaction mixture. He made the same observations when this element was treated with hydrochloric acid. Suggest how can he identify the produced gas. Write chemical equations for both the reactions.

$A$ metal $M$ does not liberate hydrogen from acids but reacts with oxygen to give a black coloured product. Identify $M$ and the black coloured product,and also explain the reaction of $M$ with oxygen.

Give one most suitable word for the following statements.
$(a)$ Metal oxides which show basic as well as acidic behaviour.
$(b)$ Iodine,a non-metal is shining.

What is the molecular formula of sodium aluminate?