combines with oxygen to form carbon dioxide water and energy.

Choose the right word and fill in the blank provided below.

Silver articles get tarnished after sometime when exposed to air because of the formation of _____. (silver sulphide, copper sulphide)

_____ reacts with metals and non-metals and forms their oxides.

(Sulphur, Nitrogen, Oxygen, Carbon dioxide, Lighter, Oxygen, Air pollution, CFCs)

Complete the statement by filling the gaps using appropriate term from the terms given in the bracket.
(slow, coloured, arrow, fast, smell, milky, physical, product, chemical, reactant, covalent, ionic, octet, duplet, exchange, sharing, equality sign) 

Oxygen is a _____ in respiration.

Burning is an example of _____. (Distillation/Combustion)

The type of flame produced by a fuel depends on the proportion of _____ available for burning the fuel.

Choose correct word from below:

Red, white              Spontaneous             Pinewood             Oxygen             Rapid

Complete the following reaction sequence showing the rusting of iron.

 _{$3\mathrm{Fe}+{\mathrm{O}}_2+$_____$\to 3\mathrm{FeO}+{\mathrm{H}}_2$}

Form similar pair of words.

Nitrogen and _____ / oxygen and $21\%$.