Give reasons :
A burning candle stops burning if covered with a glass tumbler.

Burning is a

Hydrogen burns in air with a

What do you observe when (a) Ice cold water is filled in a glass tumbler. (b) A burning candle is covered with an inverted jar. (c ) Carbon dioxide gas is passed through lime water. (d) A beam of light is allowed to enter in a closed dark room through a small hole.

Mg burns in air to give

Give reasons for: 'It is dangerous to sleep in a closed room in which a coal fire is burning'.

Give four reasons why burning of a magnesium ribbon in air is considered a chemical change.

Give reasons : Impure diamond is used to cut glass.

Burning and respiration require oxygen.

A burning candle shows both physical and chemical changes. Explain.

Give reasons : A candle brought near the mouth of a jar containing hydrogen gas starts burning but is extinguished when pushed inside the jar.