universe & solar system section 10 MCQ Questions & Answers Detailed Explanation

Answer: (a)

Answer: (c)

Answer: (a)

The word “pulsar” is a contraction of “pulsating star. A pulsar is formed when a massive star collapse exhausts its supply of fuel. It blasts out in a giant explosion known as a supernova, the most powerful and violent event in the universe.

Without the opposing force of nuclear fusion to balance it, gravity begins to pull the mass of the star inward until it implodes.

In a pulsar, gravity compacts the mass of the star until it forms an object composed primarily of neutrons packed so tightly that they no longer exist as normal matter.

As the star collapses, it begins to spin more rapidly in what is known as the conservation of angular momentum. The process is similar to that of an ice skater pulling their arms in close to spin faster. What is left behind is a rapidly spinning ball of tightly packed neutrons inside an iron shell.

Answer: (b)

Answer: (d)

Venus is smaller in size than the Earth. Diameter of earth is12,742 km while that of Venus is 12,100 km

Answer: (c)

A solar eclipse occurs when the moon crosses the path between the sun and the earth. The darkest shadow (where the sun is completely covered) is called the umbra.

The umbra is narrow at the distance of the Earth, and a total eclipse is observable only within the narrow strip of land or sea over which the umbra passes. The partial shadow is called the penumbra.