Answer: B

Explanation:

1. Unimaginably small volume: A singularity is a point in spacetime where the density and gravity are predicted to be infinite. This means it would have zero volume, or an unimaginably small size. Hence, it is correct.

2. Infinite temperature: The laws of physics as we know them break down at singularities, and one of the consequences is that temperatures would reach infinity. Hence, it is correct.

3. Very low density: This is incorrect. Singularities are actually characterized by infinite density, not very low density. This means that an infinite amount of matter would be compressed into an infinitely small point. Hence, it is not correct.

Answer: C

Explanation:

The formation of galaxies indeed begins with the accumulation of giant clouds made primarily of hydrogen gas. These clouds, called giant molecular clouds, can be hundreds of light-years across and contain millions or even billions of solar masses of gas. Gravity plays a crucial role in pulling this gas together, leading to the eventual formation of galaxies. Hence, statement 1 is correct.

Eventually, growing nebula develops localised clumps of gas. These clumps continue to grow into even denser gaseous bodies, giving rise to formation of stars. The formation of stars is believed to have taken place some 5-6 billion years ago. Hence, statement 2 is correct.

Answer: D

Explanation:

Sun (Star): The central star of our solar system, around which all other objects orbit.

Planet: A large, celestial body that orbits the Sun and has cleared the neighborhood around its orbit. We have eight planets in our solar system: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune.

Satellite: A natural object that orbits a planet or dwarf planet. Our solar system has hundreds of known moons, with Earth having one (the Moon), Jupiter having 79, Saturn having 82, and so on.

Comet: A celestial body made up of ice, dust, and rock that orbits the Sun. Comets have highly eccentric orbits, taking them far beyond the orbit of Neptune at their farthest point.

Dust particles: Tiny particles of ice and rock that orbit the Sun, mostly concentrated in the asteroid belt between Mars and Jupiter and in the Kuiper Belt beyond Neptune.

Asteroid: Rocky, airless remnants from the formation of the solar system that orbit the Sun, primarily in the asteroid belt between Mars and Jupiter.

Hence, all are correct.

Answer: A

Explanation:

Jovian planets, mainly composed of lighter gases like hydrogen and helium, have lower densities than the terrestrial planets made of denser rocky materials. Hence, statement 1 is correct.

Jupiter and Saturn are assumed to have formed first and fastest in the solar system's initial 10 million years. Rocky planets develop in the warmest areas of the disk, closer to the star. There isn't much gas left for the terrestrial planets to accrete once the icy giants form. Rocky planets such as Mercury, Venus, Earth, and Mars may take tens of millions of years to form after the star is born. Hence, statement 2 is not correct.

All Jovian planets have thick atmospheres, primarily composed of hydrogen and helium. However, the composition and structure of their atmospheres differ significantly from those of terrestrial planets. Hence, statement 3 is not correct.

Answer: B

Explanation:

Asteroids are indeed small, rocky bodies primarily composed of metals and minerals like iron and nickel. Comets, on the other hand, are made up of ice, dust, and rocky or metallic particles. Hence, statement 1 is correct.

While most asteroids are found in the asteroid belt between Mars and Jupiter, comets primarily reside in the far outer solar system, in the Oort Cloud beyond Neptune. Only a small fraction of comets venture closer to the Sun, where they become visible. Hence, statement 2 is not correct.

One of the most noticeable differences between asteroids and comets is the presence of a tail. Comets develop a glowing tail, made of dust and gas released as the ice heats up when they get close to the Sun. Asteroids, lacking significant amounts of ice, do not exhibit such tails. Hence, statement 3 is correct.