Science
2.1. Why does a marble tile would feel cold as compared to a
wooden tile on a winter morning? Give reason.
2.2. Why cotton garment cannot keep us as warm in winter as a
woolen sweater does?
Which of the two absorbs more radiation dark coloured or light
coloured object? Give reason.
Why rooms are provided with ventilators and exhaust fans near
top of side walls?
2.5. Wheat dough if left in the open, often few days starts to emit
foul smell give reason.
2.6.
Learn and write the symbols of the Elements (Do in roug
copy) Hydrogen, Nitrogen, Carbon, Sodium, Potassiu
Aluminium, Copper, Zinc, Iron, Oxygen, Calcium, Magnesium
Answers
2.1. A marble tile would feel cold as compared to a wooden tile on a winter morning because the marble tile
a) is a better conductor of heat than the wooden tile
b) is polished while wooden tile is not
c) reflects more heat than wooden tile
d) is a poor conductor of heat than the wooden tile
2.2. Cotton clothes are thin and do not have spaces in which air can be trapped. Thus, cotton clothes do not prevent heat coming out of our body. Woollen clothes keep us warm during winter because wool is a poor conductor of heat and has air trapped between the fibres.
2.5. When the wheat dough is kept open for few days, the formation of fungus and reproduction of yeast takes place. These fungi and yeast will become unfit for eating or for use. Since the formation of fungus takes place in the dough, it gives a foul smell.