Question 1. Fill up the blanks in the following:

• (a) The process of changing of water into its vapour is called _________________.
• (b) The process of changing water vapour into water is called _________________.
• (c) No rainfall for a year or more may lead to _________________ in that region.
• (d) Excessive rains may cause _________________.

Answer:-

• (a) The process of changing of water into its vapour is called evaporation.
• (b) The process of changing water vapour into water is called condensation
• (c) No rainfall for a year or more may lead to drought in that region.
• (d) Excessive rains may cause flood.

Question 2. State for each of the following whether it is due to evaporation or condensation:

• (a) Water drops appear on the outer surface of a glass containing cold water.
• (b) Steam rising from wet clothes while they are ironed.
• (c) Fog appearing on a cold winter morning.
• (d) Blackboard dries up after wiping it.
• (e) Steam rising from a hot girdle when water is sprinkled on it.

Answer:-

• (a) Water drops appear on the outer surface of a glass containing cold water. ( Condensation )
• (b) Steam rising from wet clothes while they are ironed.  ( Evaporation )
• (c) Fog appearing on a cold winter morning.   ( Condensation )
• (d) Blackboard dries up after wiping it. ( Evaporation )
• (e) Steam rising from a hot girdle when water is sprinkled on it.  ( Evaporation )

Question 3. Which of the following statements are “true” ?

• (a) Water vapour is present in air only during the monsoon. ( )
• (b) Water evaporates into air from oceans, rivers and lakes but not from the soil.( )
• (c) The process of water changing into its vapour, is called evaporation.( )
• (d) The evaporation of water takes place only in sunlight.( )
• (e) Water vapour condenses to form tiny droplets of water in the upper layers of air where it is cooler.( )

Answer:-

• (a) Water vapour is present in air only during the monsoon. ( False )
• (b) Water evaporates into air from oceans, rivers and lakes but not from the soil.( False )
• (c) The process of water changing into its vapour, is called evaporation.( True )
• (d) The evaporation of water takes place only in sunlight.( False )
• (e) Water vapour condenses to form tiny droplets of water in the upper layers of air where it is cooler.( True )

Question 4. Suppose you want to dry your school uniform quickly. Would spreading it near an anghiti or heater help? If yes, how?

Answer:- Yes, drying school uniform near anghiti or heater would definitely work because rate of evaporation becomes high when temperature increases.

Question 5. Take out a cooled bottle of water from refrigerator and keep it on a table. After some time you notice a droplets of water around it. Why?

Answer:-  Because in refrigerator there is condensation of water-vapour from air on the surface of water bottle too. After it comes outside the refrigerator it melts and thus we can notice a droplets of water around it.

Question 6. To clean their spectacles, people often breathe out on glasses to make them wet. Explain why the glasses become wet.

Answer:- When we breathe out the water vapour from our mouth get condense at the surface of spectacles. With the tiny amount of this water it becomes super easy to clean the spectacles.

Question 7. How are clouds formed?

Answer:- The water present on the earth surface evaporates due to sun heat. This water vapour in the air at high altitude, condenses to form tiny droplets of water which appears as clouds. Thus clouds are formed.

Question 8. When does a drought occur?

Answer:- If there is no rain for for many years at a place then there is scarcity of water in that region. This leads to drought.