In text questions page number 10
Question 1. Why does a desert cooler cool better on a hot dry day?
Answer: A desert cooler cools better on a hot dry day because on a hot dry day temperature is high and humidity is less which helps in better evaporation. Due to the higher rate of evaporation it gives better cooling effect.
Question 2. How does the water kept in an earthen pot (matka) become cool during summer?
Answer: The water kept in an earthen pot (matka) becomes cool during summer because of the evaporation of water through the fine holes in the earthen pot which makes it cool.
Question 3. Why does our palm feel cold when we put some acetone or petrol or perfume on it?
Answer: When we put some acetone, petrol or perfume it starts evaporating by using the energy from palm and leaving it cool.
Question 4. Why are we able to sip hot tea or milk faster from a saucer rather than a cup?
Answer: We are able to sip tea, milk faster from a saucer because it has larger surface area than the cup, In larger surface area rate of evaporation is faster due to which tea or milk cools rapidly.
Question 5. What type of clothes should we wear in summer?
Answer: During summer we should wear cotton cloths because they are good absorber of water. As Cotton cloths absorbs sweat rapidly resulting in higher rate of evaporation Due to which our body feels cool.