Olympiad Test Level 2: Our Earth and Universe- 2 - Class 7 MCQ

Jupiter has the maximum number of moons among the given planets.
Explanation:
- The number of moons for each planet in the given options are as follows:
- Jupiter: 79 known moons
- Saturn: 82 known moons
- Uranus: 27 known moons
- Neptune: 14 known moons
- Based on the given information, it can be concluded that Jupiter has the highest number of moons among the listed planets.
- The number of moons for each planet has been confirmed through scientific observations and data analysis.
- Jupiter's large size and strong gravitational pull make it capable of capturing and retaining a significant number of moons.
- The moons of Jupiter vary in size, with the four largest ones known as the Galilean moons: Io, Europa, Ganymede, and Callisto.
- These moons were discovered by Galileo Galilei in 1610 and are among the most interesting objects in the solar system.
- The numerous moons of Jupiter provide valuable insights into the formation and evolution of the planet and its surrounding environment.
- Further research and exploration continue to reveal more details about Jupiter's moon system.

In Solar System, seventh planet from Sun is Uranus.

An eclipse takes place when one heavenly body such as a moon or planet moves into the shadow of another heavenly body.

A star that is produced by a supernova is Neutron.

Explanation:
To determine which planet has the longest day in the solar system, we need to consider the rotation period of each planet. The rotation period refers to the time it takes for a planet to complete one full rotation on its axis.
Here is a breakdown of the rotation periods for each planet:
- Mercury: Mercury has a rotation period of approximately 58.6 Earth days.
- Jupiter: Jupiter has a rotation period of approximately 9.9 Earth hours.
- Venus: Venus has a rotation period of approximately 243 Earth days.
- Earth: Earth has a rotation period of approximately 24 hours.
From the given options, it can be observed that Venus has the longest rotation period with approximately 243 Earth days. Therefore, Venus has the longest day among the listed planets.
Summary:
- Mercury has a rotation period of 58.6 Earth days.
- Jupiter has a rotation period of 9.9 Earth hours.
- Venus has a rotation period of 243 Earth days.
- Earth has a rotation period of 24 hours.
- Among the listed planets, Venus has the longest day with a rotation period of approximately 243 Earth days.

The incorrect way to conserve natural resources is mentioned as option C: deforestation. Deforestation refers to the removal of trees and vegetation from an area, which leads to the depletion of natural resources and can have negative impacts on the environment.
Here are some different ways to conserve natural resources:
1. Preventing wastage: This involves using resources efficiently and minimizing waste generation.
2. Save water: Conserving water is crucial as it is a finite resource. This can be done by fixing leaks, using water-saving appliances, and practicing responsible water usage.
3. Afforestation: This process involves planting trees and creating forests, which helps to restore and conserve natural resources such as air quality, water supply, and biodiversity.
4. Energy conservation: Conserving energy helps to reduce the consumption of fossil fuels, which are non-renewable resources. This can be achieved through practices like using energy-efficient appliances, insulating buildings, and promoting renewable energy sources.
5. Recycling: Recycling helps to conserve natural resources by reducing the need for raw materials. It involves reprocessing waste materials into new products, which saves energy and reduces pollution.
6. Reducing pollution: Minimizing pollution helps to protect natural resources such as air, water, and soil. This can be done by using environmentally friendly products, practicing proper waste disposal, and reducing emissions.
By adopting these conservation methods, we can contribute to the preservation and sustainable use of natural resources for future generations.

How to keep the environment clean and green:
There are several ways to maintain a clean and green environment, and these methods can be categorized into the following key points:
1. Using less energy:
- This involves reducing energy consumption in everyday activities, such as turning off lights and appliances when not in use.
- Opting for energy-efficient appliances and using renewable energy sources like solar or wind power.
- Insulating homes and buildings properly to conserve energy.
2. Using environment-friendly technology:
- Utilizing eco-friendly technology helps to reduce pollution and minimize the environmental impact.
- Using electric vehicles or public transportation instead of gasoline-powered cars.
- Implementing recycling and waste management systems to properly dispose of waste and reduce landfill contribution.
3. Protecting wildlife:
- Preserving natural habitats and preventing deforestation to protect wildlife and maintain biodiversity.
- Supporting conservation efforts and organizations that focus on preserving endangered species.
- Avoiding the use of harmful pesticides and chemicals that can harm wildlife and their habitats.
4. All of the above:
- The most effective way to keep the environment clean and green is by implementing all of the above-mentioned practices.
- Combining efforts to reduce energy consumption, use eco-friendly technology, and protect wildlife will have a significant positive impact on the environment.
In conclusion, by adopting practices such as using less energy, utilizing environment-friendly technology, and protecting wildlife, we can collectively contribute to maintaining a clean and green environment. It is essential for individuals, communities, and governments to work together to create a sustainable future for generations to come.

What is a tornado?

A tornado is a specific type of severe weather phenomenon characterized by a violent, twisting funnel of wind. It is often associated with severe thunderstorms and can cause significant damage and destruction.

Key Points:

• Tornadoes are formed from powerful thunderstorms.


• They typically develop from large, rotating updrafts called supercells.


• The rotation in a tornado is caused by wind shear, which is a change in wind direction and speed with height.


• Tornadoes can have wind speeds of up to 300 miles per hour (482 kilometers per hour) or more.


• They are usually characterized by a narrow, funnel-shaped cloud extending from the base of a thunderstorm to the ground.


• Tornadoes can vary in size and intensity, ranging from weak and short-lived to strong and long-lasting.


• They can cause damage to buildings, trees, and infrastructure, as well as pose a significant threat to human life.


• Tornadoes are most commonly observed in the United States, particularly in an area known as Tornado Alley, but they can occur in many other parts of the world as well.

Overall, tornadoes are powerful and destructive weather phenomena that require caution and preparedness to mitigate their impact on communities and individuals.

Explanation:
The reason why the pole star is always seen at the same point in the sky is because it lies in the axis of spin of the Earth. This means that it is aligned with the Earth's rotational axis, also known as the North Pole. Here's a detailed explanation:
Earth's Axis of Rotation:
- The Earth rotates around an imaginary line called its axis of rotation.
- The axis of rotation is an imaginary line that passes through the North Pole and the South Pole.
- This axis is tilted at an angle of about 23.5 degrees with respect to the plane of the Earth's orbit around the Sun.
Pole Star:
- The pole star, also known as Polaris, is a star located very close to the Earth's rotational axis in the northern hemisphere.
- Due to its alignment with the Earth's axis of rotation, Polaris appears almost stationary in the night sky.
- It is located directly above the North Pole, and all other stars appear to revolve around it in circular paths.
- This is why the pole star is always seen at the same point in the sky, regardless of the time of night or the season.
Advantages of the Pole Star:
- The pole star has been used for navigation by different cultures throughout history.
- Its fixed position in the sky makes it a reliable reference point for determining direction.
- By observing the angle between the pole star and the horizon, sailors and travelers can determine their latitude.
Conclusion:
The pole star appears to be always seen at the same point in the sky because it lies in the axis of spin of the Earth. This alignment with the Earth's rotational axis gives it a fixed position relative to the observer on Earth, making it a valuable navigational tool and reference point for determining direction and latitude.

Venus, which can be seen with the unaided eye fromEarth, is the brightest planet in our Solar System.Venus was given the nickname evening star and morning star because of its bright, consistent presence