Page 188 - ICSE Chemistry 8

5. Metals posi oned above _____________ in the reac vity series react vigorously with cold water
and o en catch fi re.
6. Temporary hardness of water can be removed by _____________.

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

1. Filtered water is sterilised to remove harmful bacteria by adding sulphur. ______________
2. Muddy water can be cleaned by adding a crystal of copper sulphate. ______________

3. A solu on that contains more dissolved substance than could normally be
dissolved at a specifi c temperature is called saturated solu on. ______________

4. A true solu on is a heterogeneous solu on which consists of solid par cles
having par cle size of above 10,000 Angstrom. ______________
5. Effl orescence refers to the process of absorbing moisture from air which is
not suffi cient to transform the state of a substance. ______________

6. The chemical name of blue vitriol is zinc sulphate heptahydrate. ______________

C. Match the columns.
Column A Column B Column C

1. Rainwater (a) Maximum density at (i) Fit for drinking
4°C

2. Surface water (b) From clouds (ii) Bad conductor of heat and
electricity
3. Potable water (c) Bicarbonates of calcium and (iii) Not removed by boiling
magnesium

4. Pure water (d) Free from harmful substances (iv) Purest form of water
5. Temporary hardness (e) Oceans and seas (v) Removed by boiling

6. Permanent hardness (f) Chlorides and sulphates of (vi) Unfi t for consump on
calcium and magnesium

D. Choose the correct op on.
1. Which of the following processes takes place without water in humans?

(a) Diges on of food (b) Breathing
(c) Excre on of waste (d) Maintenance of body temperature

2. For which of the following process(es) do plants need water?
(a) Photosynthesis (b) Transporta on of minerals

(c) Both (a) and (b) (d) None of these

3. Pure water is _________________.
(a) acidic (b) neutral (c) basic (d) both acidic and basic

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