Which metals do not corrode easily?

Define the following terms:
$(i)$ Mineral
$(ii)$ Ore
$(iii)$ Gangue

$A$ man went door to door posing as a goldsmith. He promised to bring back the glitter of old and dull gold ornaments. An unsuspecting lady gave a set of gold bangles to him which he dipped in a particular solution. The bangles sparkled like new but their weight was reduced drastically. The lady was upset but after a futile argument the man beat a hasty retreat. Can you play the detective to find out the nature of the solution he had used?

Explain the meanings of malleable and ductile.

Name two metals which are found in nature in the free state.

Give reasons: Aluminium is a highly reactive metal,yet it is used to make utensils for cooking.