Class 7 CBSE Guide | Sample Question Answers | Our Changing Earth - NCERT Geography

Class 7 CBSE Guide NCERT Solutions  >  7th Geography (Our Environment)   

Our Changing Earth

Chapter 3, NCERT Geography (Our Environment)

Class 7 CBSE Guide - Sample Question Answers

Question: What are lithosphere plates?

Answer: The earth’s lithosphere is broken into a number of very large pieces known as ‘Lithosphere Plates’. For example, Indo-Australian Plate.

Question: Give reasons for the movement of lithosphere plates.

Answer: The lithosphere plates are moving at a very slow rate of just a few millimeters a year. Due to the earth’s movement the magma which is present inside the earth is also moving. This is the reason for the movement of lithosphere plates which are floating on the molten magma.   

Question: Name five rivers in different countries which form deltas.

Answer: 1. Ganges (India)

2. Nile (Egypt)

3. Mississippi (US)

4. Amazon (Brazil, South America)

5. Irrawaddy (Myanmar)

6. Murray (Australia)

Question: What is a ‘Volcano’? Can you name a few volcanoes and their countries?

Answer: A ‘Volcano’ is a vent in the earth’s crust through which molten materials erupt suddenly. Following are the names of some volcanoes with their countries:

1. Mount Vesuvius (Italy)

2. Mount St. Helens (Washington, US)

3. Mauna Loa (Hawaii, US)  

4. Krakatoa (Indonesia)

Question: How do earthquakes occur? Give example.

Answer: Due to the sudden rapid movement of lithosphere plates, the surface of the earth starts vibrating. These vibrations are called earthquake. Earthquakes also occur when energy stored within the Earth, generally in the form of strain in rocks, is suddenly released. This energy is transmitted to the surface of the Earth by earthquake waves.

A massive earthquake measuring 6.9 on Richter scale hit Bhuj town in Gujarat on 26^th January, 2001.

Question: Define 1. Focus 2. Epicenter

Answer:

Focus - The point within the Earth from where an earthquake originates is called the focus. Earthquake waves begin to radiate out from the focus and travel all around.

Epicentre - The point on the Earth’s surface directly above the focus is called the epicentre. This is the area which suffers the greatest damage. As we go away from epicenter, the earthquake intensity decreases.

Question: List the outcomes (terms) of the work of a river.

Answer: Following are the outcomes due to the work of a river -

• Waterfall
• Meanders
• Oxbow Lake
• Floodplain
• Levees
• Delta

Question: List the outcomes (terms) of the work of ice or glacier.

Answer: Following are the outcomes due to the work of ice or glacier -

• Lakes
• Moraines

Question: List the outcomes (terms) of the work of wind.

Answer: Following are the outcomes due to the work of wind -

• Mushroom rocks
• Sand dunes
• Loess

Question: List the outcomes (terms) of the work of sea waves.

Answer: Following are the outcomes due to the work of sea-waves -

• Sea caves
• Sea arches
• Stacks
• Sea-cliff
• Beach

Question: Name a few waterfalls in India

Answer:  Some of the famous waterfalls in India are:

• Dhuandhar waterfalls (M.P.)
• Hundru waterfall (Jharkhand)
• Jog waterfall (Karnataka)

Class 7 Our Changing Earth (Exercise Question Answers) - also study

Our Changing Earth - CBSE Guide and NCERT Solutions for Chapter 3, Class 7 Geography Our Environment