Practicing Class 9 Science MCQ and Class 9 Science Exploration Chapter 13 MCQ Online Test with Answers Earth as a System Energy Matter and Life daily helps in time management.
Class 9 Science Chapter 13 Earth as a System Energy Matter and Life MCQ
Earth as a System Energy Matter and Life MCQ
Class 9 Science Chapter 13 MCQ online test
Question 1.
The fraction of solar radiation reflected by a surface is called its:
(a) Insolation
(b) Solar constant
(c) Albedo
(d) Electromagnetic spectrum
Answer:
(c) Albedo
Question 2.
Which atmospheric layer is responsible for nearly all weather phenomena such as winds, storms and rainfall?
(a) Stratosphere
(b) Mesosphere
(c) Thermosphere
(d) Troposphere
Answer:
(d) Troposphere
Question 3.
During the day in mountainous regions, the flow of cooler air from the valley up the heated mountain slopes is called a:
(a) Mountain breeze
(b) Valley breeze
(c) Planetary wind
(d) Trade wind
Answer:
(b) Valley breeze
Question 4.
Which of the following bacteria is responsible for converting nitrite (\(N \mathrm{O}_2^{-}\)) into nitrate (\(N \mathrm{O}_3^{-}\)) during nitrification?
(a) Rhizobium
(b) Azotobacter
(c) Nitrosomonas
(d) Nitrobacter
Answe
(d) Nitrobacter
Question 5.
Excess CO2 released from human activities enhances the greenhouse effect primarily because:
(a) It directly absorbs incoming UV radiation from the Sun
(b) It traps outgoing infrared radiation re-radiated from Earth’s surface
(c) It reflects more sunlight back into space, warming the poles
(d) It increases the solar constant reaching the Earth’s surface
Answer:
(b) It traps outgoing infrared radiation re-radiated from Earth’s surface
Earth as a System Energy Matter and Life Class 9 Assertion and Reason Questions
Directions: For Questions number (i) to (ii), two statements are given — one labelled as Assertion (A) and the other labelled as Reason (R). Select the correct answer to these questions from the codes (a), (b), (c) and (d) as given below.
(a) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
(b) Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of Assertion (A).
(c) Assertion (A) is true, but Reason (R) is false.
(d) Assertion (A) is false, but Reason (R) is true.
Question 1.
Assertion (A): Equatorial regions remain relatively warm throughout the year, while polar regions experience much colder conditions.
Reason (R): The Sun’s radiation falling on the equatorial region is concentrated over a smaller area, whereas in polar regions it is spread over a larger area.
Answer:
(a) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
Explanation:
The Earth is spherical and because of that the Sun’s rays strike different latitudes at different angles. At the equator, radiation is concentrated over a small area, while at the poles it is spread over a larger area, causing uneven heating and the observed temperature differences.
Question 2.
Assertion (A): Cities are warmer than surrounding rural areas, especially during summer and at night.
Reason (R): Rural areas and forests have more vegetation which absorbs solar radiation more efficiently than urban materials.
Answer:
(c) Assertion (A) is true, but Reason (R) is false.
Explanation:
The Urban Heat Island Effect states that cities are warmer than rural areas. Cities are warmer in that urban materials like steel, concrete, brick, and asphalt absorb and retain more solar radiation and re-radiate more heat.
Earth as a System Energy Matter and Life Class 9 Fill in the Blanks
1. The average solar energy received per unit time per unit area at the top of Earth s atmosphere is called the ___________, and its value is approximately ___________ kWm-2.
Answer:
Solar constant; 1.4 kWm-2 (or 1400 J s-1m-2)
2. The cyclic movement of matter and energy between the living (biotic) and non-living (abiotic) components of the Earth is called the _________.
Answer:
Biogeochemical cycle
3. The widespread growth of algae in water bodies caused by excessive nitrogen from fertilisers, which depletes oxygen and kills fish, is called ___________.
Answer:
Eutrophication
4. Large circular patterns of moving ocean water masses formed due to the deflection caused by Earth s rotation are called _________. They rotate _________ in the Northern Hemisphere.
Answer:
Gyres; clockwise
5. Human activities have raised atmospheric CO2 by about _________ % since 1960, from _________ ppm to _________ ppm.
Answer:
35 % ; 315 ppm to 420 ppm.
Earth as a System Energy Matter and Life Class 9 True or False
1. Snow has a lower albedo than black soil, which is why polar regions are colder.
Answer:
False
(Reason: Snow has a very HIGH albedo (0.80 – 0.90), meaning it reflects most incoming solar radiation and absorbs very little, which is why polar regions are cold. Black soil has a LOW albedo, absorbs more radiation, and is therefore warmer. Table 13.1 states snow (0.80 – 0.90) and crushed rock (0.25 – 0.30). Lower albedo surfaces absorb more.)
2. Nearly all weather phenomena take place in the troposphere.
Answer:
True
(Reason: Nearly all weather phenomena take place in the troposphere because it is heated from below by Earth’s surface, causing temperature to decrease with height, which drives the convection currents, winds, and storms that constitute weather.)
3. Nitrogen gas (N2) from the atmosphere can be directly absorbed and used by plants.
Answer:
False
(Reason: Nitrogen gas (N2) is rather non-reactive, and cannot be directly used by plants and animals. It must first be converted to soluble compounds such as ammonia, nitrite, nitrate through nitrogen fixation by bacteria like Rhizobium and Azotobacter before plants can absorb it.)
4. The ozone layer is located in the troposphere and protects Earth from harmful UV radiation.
Answer:
False
(Reason: The ozone layer is located in the stratosphere (12 – 50 km), not the troposphere. The ozone layer in the stratosphere absorbs harmful UV radiation, heating that layer and causing temperature to rise with height there. Ground-level ozone, formed by vehicular emissions reacting with sunlight, is actually harmful to health.)
5. The North Atlantic Drift keeps many ports on the northwestern coast of Europe ice-free during winter.
Answer:
True
(Reason: The North Atlantic Drift is an extension of the Gulf Stream, a strong ocean current that carries warm water from the southern North American east coast across the Atlantic Ocean toward the northwestern coast of Europe. This warm current moderates the climate and keeps many European ports ice-free even at high latitudes during winter.)
Earth as a System Energy Matter and Life Class 9 Match the Following
Question 1.
Match the following items given in Column A with that in Column B:
| Column A | Column B |
| 1. Nitrogen fixation | (a) Decomposers |
| 2. Converts NH3 to \(N \mathrm{O}_2^{-}\) | (b) Nitrobacter |
| 3. Converts \(N \mathrm{O}_2^{-}\) to \(N \mathrm{O}_3^{-}\) | (c) Pseudomonas |
| 4. Denitrification | (d) Rhizobium / Azotobacter |
| 5. Ammonification | (e) Nitrosomonas |
Answer:
| Column A | Column B |
| 1. Nitrogen fixation | (d) Rhizobium / Azotobacter |
| 2. Converts NH3 to \(N \mathrm{O}_2^{-}\) | (e) Nitrosomonas |
| 3. Converts \(N \mathrm{O}_2^{-}\) to \(N \mathrm{O}_3^{-}\) | (b) Nitrobacter |
| 4. Denitrification | (c) Pseudomonas |
| 5. Ammonification | (a) Decomposers |
Question 2.
Match the following items given in Column A with that in Column B:
| Column A | Column B |
| 1. Geosphere | (a) Elimalayan glaciers and snow in Ladakh |
| 2. Elydrosphere | (b) Mangroves, forests, ocean plankton |
| 3. Cryosphere | (c) Deccan Plateau, Thar Desert |
| 4. Atmosphere | (d) Ganga-Brahmaputra river system |
| 5. Biosphere | (e) Nitrogen (78 %) and oxygen (21 %) |
Answer:
| Column A | Column B |
| 1. Geosphere | (c) Deccan Plateau, Thar Desert |
| 2. Hydrosphere | (d) Ganga-Brahmaputra river system |
| 3. Cryosphere | (a) Himalayan glaciers and snow in Ladakh |
| 4. Atmosphere | (c) Deccan Plateau, Thar Desert |
| 5. Biosphere | (b) Mangroves, forests, ocean plankton |
MCQ On Earth as a System Energy Matter and Life Class 9 for Practice
Choose the correct option in the following questions
Question 1.
Which of the following correctly describes the solar constant?
(a) The total energy radiated by the Sun per second
(b) The average solar energy received per unit time per unit area at the top of Earth’s atmosphere
(c) The amount of insolation reaching Earth’s surface under clear sky conditions
(d) The energy trapped by greenhouse gases per unit area
Question 2.
The process by which decomposers break down dead organic matter and return nitrogen compounds like ammonia to the soil is called:
(a) Nitrification
(b) Denitrification
(c) Ammonification
(d) Nitrogen fixation
Question 3.
Which of the following statements about the stratosphere is correct?
(a) Temperature decreases with height and all weather occurs here
(b) The ozone layer is located here and temperature increases with height
(c) It contains 78% nitrogen and 21% oxygen
(d) It is the layer where gyres and ocean currents are formed
Question 4.
Ocean currents form large circular patterns called gyres due to:
(a) Differences in salinity alone
(b) The uneven heating of the equator and poles
(c) The deflection caused by Earth’s rotation
(d) The depth of the ocean floor at different locations
Question 5.
Which of the following is a consequence of deforestation as described in the chapter?
(a) Increased groundwater recharge due to more surface runoff
(b) Decrease in soil erosion because tree roots are removed
(c) Decrease in local rainfall due to reduced transpiration
(d) Increase in albedo leading to warming of the region
Assertion-Reason Questions
Directions: For Questions number (i) to (ii), two statements are given – one labelled as Assertion (A) and the other labelled as Reason (R). Select the correct answer to these questions from the codes (a), (b), (c) and (d) as given below.
(a) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
(b) Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of Assertion (A).
(c) Assertion (A) is true, but Reason (R) is false.
(d) Assertion (A) is false, but Reason (R) is true.
Question 1.
Assertion (A): Black soil and ocean water are relatively warmer than snow-covered surfaces.
Reason (R): Black soil and ocean water have lower albedo, meaning they absorb more solar radiation than snow, which has a very high albedo.
Question 2.
Assertion (A): Excess CO2 in the atmosphere is harmful even though plants require it for photosynthesis.
Reason (R): Excess CO2 enhances the greenhouse effect, causing global warming, melting of glaciers, rising sea levels, ocean acidification, and more extreme weather conditions.
Fill in the Blanks
1. The word ‘albedo’ comes from the Latin word meaning _________, and surfaces with _________albedo stay cool because they reflect more light.
2. The troposphere has an average height of about _________ km, and temperature in this layer decreases with height at the rate of approximately _________ °C per km.
3. In the nitrogen cycle, the bacteria converts nitrite (\(N \mathrm{O}_2^{-}\)) into nitrate (\(N \mathrm{O}_3^{-}\)) while _________ converts some nitrates back into nitrogen gas, completing the cycle.
4. Carbon forms the backbone of life – every _________, carbohydrate, fat and DNA molecule contains carbon.
5. The widespread growth of algae in water bodies caused by excessive nitrogen from fertilisers is called _________. This process depletes _________ in the water and kills fish.
State whether the statements given below are True or False
1. The maximum insolation reaching Earth’s surface under clear sky conditions is equal to the solar constant, which is 1.4 kWm-2.
2. In mountainous regions, after sunset, cool dense air from the slopes flows down into the valley — this is called a valley breeze.
3. About 99% of the Sun’s energy reaching Earth is concentrated in the ultraviolet, visible, and infrared range of the electromagnetic spectrum.
4. Burning of fossil fuels and deforestation have raised atmospheric CO2 by about 35% since 1960, from 315 ppm to 420 ppm.
5. The atmosphere consists mainly of oxygen (78 %) and nitrogen (21 %).
Match the Columns
Question 1.
Match the following items given in Column A with that in Column B:
| Column A | Column B |
| 1. Troposphere | (a) Temperature increases with height; ozone layer present |
| 2. Stratosphere | (b) Plays only a minor role in regulating climate |
| 3. Mesosphere | (c) Temperature decreases with height; all weather occurs here |
| 4. Thermosphere | (d) Located above the mesosphere |
| 5. Exosphere | (e) Region beyond which outer space begins, ~ 100 km above Earth |
Question 2.
Match the following items given in Column A with that in Column B:
| Column A | Column B |
| 1. Water cycle | (a) Carbon from organisms buried over millions of years forms coal and oil |
| 2. Carbon cycle (fast) | (b) Rhizobium and Azotobacter convert N2 to ammonia |
| 3. Carbon cycle (slow) | (c) Water evaporates, condenses to form clouds, and returns as precipitation |
| 4. Nitrogen cycle | (d) Plants convert atmospheric CO2 to glucose through photosynthesis |
| 5. Oxygen cycle | (e) Plants restore O2 through photosynthesis using sunlight, water and CO2 |