The burning of matchstick is an example for chemical reaction based on______

(a)

Contact in physical states

(b)

electricity

(c)

light

(d)

catalyst

The pigment responsible for browning of apples is______.

(a)

Hydrated iron (II) oxide

(b)

melanin

(c)

starch

(d)

ozone

Limestone contains ______ mainly.

(a)

Calcium chloride

(b)

calcium carbonate

(c)

calcium nitrate

(d)

calcium sulphate

In Haber’s process of producing ammonia ______ is used as a catalyst.

(a)

Nitrogen

(b)

hydrogen

(c)

iron

(d)

nickel

______ is responsible for Global warming.

(a)

Carbon di oxide

(b)

methane

(c)

chlorofluoro carbons

(d)

all the above