A hard material X which is mined from the earth is used as a houselold fuel and also for the generation of electricity at Thermal power Stations. A soft material Y is also used as a fuel in the form of candles .A gaseous material Z which occurs alongwith petroleum is uncreasingly being used as a fuel in running vehichles in its compressed from .
(a) What are materials X,Y andZ?
(b)When materials X,Y and Z are burned separately:
(i)Which materials burns by producing a yellow , luminous flame?
(ii) Which material ultimately burns without producing a flame?
(iii) Which material can burn in a gas stove buy producing a blue flame?