Explain why burning of wood and cutting it into small pieces are considered as two different types of changes.

 Cutting of trees → Physical change   Melting of butter in a pan → Physical change   Rusting of almirah → Chemical change   Boiling of water to form steam → Physical...

(a) (i) and (ii) 

(a) Burning of wood and coal causes pollution of air.  (b) A liquid fuel used in homes is LPG.  (c) Fuel must be heated to its ignition temperature before it starts burning.  (d)...

Charcoal is considered a better fuel than wood because: (i) It has high calorific value. (ii) It does not produce any smoke. Disadvantages: (i) 1 kg of wood on destructive distillation produces only 0.25...

Wood is a renewable source of energy. It is obtained by cutting trees. A new plant sapling usually takes more than 15 years to grow and mature into a tree....

Wash, peel, cut and cook the potatoes. Cooking in a small amount of water and then frying in a small quantity of oil conserves the nutrients.

(i) hand picking; (ii) grains; (iii) sieving; (iv) sedimentation; (v) solid, liquid

Charcoal is obtained from wood by destructive distillation of wood. Charcoal is considered a better fuel than wood because  (i) it has higher calorific value than wood.  (ii) it does not produce...

(d) The asteroids are group of small pieces of rock revolving round the sun between the orbit of Mars and Jupiter. They are approximately 40,000 in number.

Most of the processes are carried out in an open system i.e, at constant pressure.