Chapter -12 (Natural Disaster)

Back exercise question and answers

Question 1: What are the main causes of floods? Write two ways in which floods can be controlled.

Answer 1: Floods occur mainly because of heavy rainfall. Collapse of dams, blocking of rivers due to landslides, cyclones, tsunamis and sudden melting of snow on mountains also cause floods.

Floods can be controlled by planting trees and building special dams to check the speed of water.

Question 2: What is drought? Suggest some measures to prevent droughts.

Answer 2: Drought means occurrence of little or no rain for a long period of time.

Droughts can be prevented in the following ways.

· Growing more trees.

· Developing rainwater harvesting systems.

· Growing drought-resistant crops such as sorghum, millets and maize.

· Spraying water directly on the base of the plants.

· Developing effective irrigation facilities.

Question 3: Why does an earthquake occur? How does it measured?

Answer 3: An earthquake occurs when there are sudden movement under Earth’s surface. A seismograph is an instrument that records earthquake tremors. The magnitude or intensity of an earthquake is measured on the Richter scale.

Question 4: What are cyclones? Which states in India are prone to cyclones?

Answer 4: Cyclones are violent storms. They form over oceans and seas. They are accompanied by heavy showers and high-speed winds.

West Bengal, Odisha, Andhra Pradesh, Tamil Nadu, Maharashtra and Gujarat are prone to cyclones.

Think and answer

Question: Ranjan said that he saw an avalanche when he went to Rajasthan. Is this true? Give reasons for your answer.

Answer: Ranjan cannot see an avalanche in Rajasthan as it is a desert region. An avalanche is a mass of snow, ice and rocks that slides down a mountain. It occur only in cold mountainous regions.