Page 144 - ICSE Chemistry 8

3. The chemical reac ons that take place in the presence of light are called _______________ reac ons.
4. A ____________ catalyst increases the rate of a reac on.

5. ________________ is an enzyme which is specifi c to the diges on of carbohydrates.

6. _______________ is a decomposi on process in which a metallic ore is heated in the absence or
limited supply of air.

B. Iden fy the error in the given statements. Circle the incorrect word and write the correct word in
the blank.

1. When solid lead nitrate is heated, green-coloured nitrogen gas
is evolved with oxygen. __________________

2. When carbon and sulphur are heated, heat energy is evolved. __________________

3. Chloroplast acts as a catalyst in the photosynthesis reac on in plants. __________________
4. Limestone is heated to form calcium hydroxide and carbon dioxide. __________________

5. An atom or a group of atoms which accepts electrons during an oxida on
reac on is called a reducing agent. __________________
6. Roas ng is a decomposi on process in which carbon dioxide is produced
with metal oxide. __________________

C. Complete and balance the following chemical equa ons.

1. Na CO + _________ _________ + H O + CO 
2
2
2
3
2. 2[Pb(NO ) ] _________ + 4NO  + O 
2
2
3 2
3. NH + HCl _________
3
4. Na SO + _________ _________ + 2NaCl
2
4
heat
5. 2FeSO _________ + __________ + SO 
4
3
6. Zn + 2NaOH __________ + H 
2
D. Write the chemical equa ons for the following.
1. When solid sodium nitrate is heated, oxygen gas is evolved.
2. When an iron nail is dipped in blue-coloured copper sulphate solu on, the blue colour of the
solu on fades and eventually turns into light green.
3. When ammonium hydroxide and iron sulphate solu ons are mixed together, a brown-coloured
precipitate of iron hydroxide is obtained.

4. Calcium carbonate on hea ng gives carbon dioxide and calcium oxide.
5. Potassium chlorate when heated in the presence of a catalyst (manganese dioxide) gives potassium
chloride and oxygen.

6. Zinc displaces copper from a solu on of copper(II) sulphate.

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