SUGGESTED SOLUTIONS
1. (a)
⮚ boiling point
⮚ Freezing point
(b) It makes the road less slippery since salt lowers the freezing point of the
water. And prevents the formation of the when the temperature drops below
00c at night
(c) Anhydrous cooper (ii) sulphate turns blue
Anhydrous copper (II) sulphate teurned blue
Anhydrous copper (II) sulphate didn’t change
Anhydrous copper (II) sulphate turned blue
2. (a) The skin felt very cold
(b) Evaporation absorbs heat from the surrounding
(c) In evaporation , molecules with low kinetic energy take heat from the
surrounding and get vaporized. When air is blown over your body that has a lot of
sweat. One feel relieved because of evaporation of sweat. These evaporation
molecules take heat energy from your body and cool it down.
3. (a) (1.5 =- 0.5)
= 1.0 min
(b) (7.2 -2.0) =5.0 mins
(c) Ice takes up heat, thus ice melts to form a liquid: water then warms up:
some evaporation occurs, causing water to boil at constant temperature of 100 0c
4. (a) White powder was formed
(b) the product cannot be reversed back to the original material/ chemical
change / permanent change
(c) The matter in the original material changed into a new product
(d) The change can be utilized in making new things
, 5. (a) Charcoal removes toxins from the water without stripping the water of
mineral salts
(b) Adding chemicals such as chlorine to kill the germs
(c) Using glass material instead of plastic
(d) Using activated charcoal instead of ordinary charcoal
6. (a) Burette
(b)(i) Sample x rain water
Reason: rain water readily forms lather with soap; hence requires the same and
least amount of soap before and after boiling.
(ii) Sample Z; temporarily hardness:
Reason; on boiling temporarily hard water required less amount of soap to form
lather; the bicarbonate in the temporary hard water are precipitated as unsoluble
carbonate.
(iii) Sample y: permanent hard water
Reason: boiling has no effect on permanent hard water. This water contains
sulphates and or/ chlorides of calcium/ and or magnesium which do not dissociate
on heating that waste soap
(c) When rain water per collates through rocks it dissolves calcium and
magnesium salts. The sulphate and chlorides form permanent hard water, while
hydrogen carbonates form temporary hard water.
7. (a) Cement contain calcium carbonate
● Tooth paste contain tin fluoride
● Fertilisers contain ammonium nitrate or potassium nitrate
● Photographic films contain silver bromide
● Dry cells contain ammonium chloride
● Medical plaster contain calcium suphate
1. (a)
⮚ boiling point
⮚ Freezing point
(b) It makes the road less slippery since salt lowers the freezing point of the
water. And prevents the formation of the when the temperature drops below
00c at night
(c) Anhydrous cooper (ii) sulphate turns blue
Anhydrous copper (II) sulphate teurned blue
Anhydrous copper (II) sulphate didn’t change
Anhydrous copper (II) sulphate turned blue
2. (a) The skin felt very cold
(b) Evaporation absorbs heat from the surrounding
(c) In evaporation , molecules with low kinetic energy take heat from the
surrounding and get vaporized. When air is blown over your body that has a lot of
sweat. One feel relieved because of evaporation of sweat. These evaporation
molecules take heat energy from your body and cool it down.
3. (a) (1.5 =- 0.5)
= 1.0 min
(b) (7.2 -2.0) =5.0 mins
(c) Ice takes up heat, thus ice melts to form a liquid: water then warms up:
some evaporation occurs, causing water to boil at constant temperature of 100 0c
4. (a) White powder was formed
(b) the product cannot be reversed back to the original material/ chemical
change / permanent change
(c) The matter in the original material changed into a new product
(d) The change can be utilized in making new things
, 5. (a) Charcoal removes toxins from the water without stripping the water of
mineral salts
(b) Adding chemicals such as chlorine to kill the germs
(c) Using glass material instead of plastic
(d) Using activated charcoal instead of ordinary charcoal
6. (a) Burette
(b)(i) Sample x rain water
Reason: rain water readily forms lather with soap; hence requires the same and
least amount of soap before and after boiling.
(ii) Sample Z; temporarily hardness:
Reason; on boiling temporarily hard water required less amount of soap to form
lather; the bicarbonate in the temporary hard water are precipitated as unsoluble
carbonate.
(iii) Sample y: permanent hard water
Reason: boiling has no effect on permanent hard water. This water contains
sulphates and or/ chlorides of calcium/ and or magnesium which do not dissociate
on heating that waste soap
(c) When rain water per collates through rocks it dissolves calcium and
magnesium salts. The sulphate and chlorides form permanent hard water, while
hydrogen carbonates form temporary hard water.
7. (a) Cement contain calcium carbonate
● Tooth paste contain tin fluoride
● Fertilisers contain ammonium nitrate or potassium nitrate
● Photographic films contain silver bromide
● Dry cells contain ammonium chloride
● Medical plaster contain calcium suphate
