Give reason: a. Some objects made of metals become dull after sometimes.
Answers
Answer:
It is the effect of air and moisture. Metals like iron, alluminium etc. ... Parts of air like hydrogen sulphide, sulphur, carbonates reacts with metals like silver (reacts with hydrogen sulphide to form silver sulphide) and copper (reacts with sulphur to form copper sulphate) which causes dullness
Answer:
Some objects made of metals become dull after sometimes.
Explanation: This is because metals react with moist air to form metal oxides which make their appereance dull. For example, when iron or iron particles are left in the contact of moist air for a long period of time, then its surface corrodes and acquires a reddish-brown substance called rust (also known as iron oxide). This takes away the lustre of iron and it appears to be dull. While iron rusts, other metals corrode.