Burning of paper is a______ change.

(a)

Physical

(b)

chemical

(c)

physical & chemical

(d)

neutral

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

(a)

Contact in physical states

(b)

electricity

(c)

light

(d)

catalyst

Brine is a concentrated solution of ______.

(a)

Sodium sulphate

(b)

sodium chloride

(c)

calcium chloride

(d)

sodium bromide

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

Rusting of iron is a _________ change.

(a)

physical

(b)

chemical

(c)

physical and chemical

(d)

neutral

Reactants → ______.

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Products

Iron objects undergo rusting when exposed to ______ and ______.

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Water and oxygen

Electrolysis of Brine solution gives ______ gases.

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Chlorine and hydrogen

______ is the enzyme responsible for browning of vegetables, fruits.

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Polyphenol oxidase or tyrosinase.

The sides of the matchbox contains _________

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Red phosphorous

Rusting

(1)

Haber's process

Thermolysis

(2)

Decomposition

Catalysis

(3)

Decomposition of limestone

Tarnishing

(4)

Chemical reaction

Calcium oxide

(5)

Iron

Fertilizers: Land pollution :: Oil spillage: _________

Iron in water and air: Brown colour :: Iron in copper sulphate solution:_________

Brine solution undergoes photolysis to give hydrogen and chlorine gas along with sodium hydroxide.

In vanaspathi ghee (dalda) preparation finely divided platinum is used as a catalyst.

Silver articles become black on exposure to atmospheric air

Define a chemical reaction.

What is pollution?

Why photosynthesis is a chemical reaction?

What is rusting?

Explain the role of yeast in making cakes and buns in a bakery?

Do all the fruits and vegetables undergo browning? Explain.

Explain the three types of pollution.

Explain any three conditions that is required for a chemical reaction to take place. Give example.