Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R).

Assertion (A): Mercury is the second farthest planet from the Sun.

Reason (R): Mercury is the smallest planet in the entire solar system.

In the light of the above statements, choose the most appropriate answer from the options given below:

(A) is not correct but (R) is correct

The correct answer is option 4. (A) is not correct but (R) is correct.

Assertion (A): Mercury is the second farthest planet from the Sun. (Incorrect)

This statement is wrong. Mercury is the closest planet to the Sun in our solar system. The planets in order of increasing distance from the Sun are:

Mercury

Venus

Earth

Mars

Jupiter

Saturn

Uranus

Neptune

Reason (R): Mercury is the smallest planet in the entire solar system. (Correct)

This statement is true. Mercury is the smallest planet, with a diameter just slightly larger than Earth's moon.

The distance a planet is from the Sun is primarily determined by the conditions during the formation of our solar system about 4.6 billion years ago. Here's a breakdown of the key factors:

Temperature: Closer to the Sun, it was extremely hot. Only materials with high melting points, like metals and rock, could survive in this intense heat. This is why the inner planets (Mercury, Venus, Earth, Mars) are rocky and relatively small.

Accretion: Dust and gas swirled around the young Sun, eventually clumping together due to gravity to form planets. The closer a clump was to the Sun, the less gas and ice it could hold onto due to the Sun's heat. This is why the inner planets have little to no gas compared to the outer gas giants.

Orbital mechanics: As the planets formed and interacted gravitationally, their orbits became more stable. The closer a planet is to the Sun, the faster it needs to travel in its orbit to maintain balance with the Sun's gravity. This explains why Mercury, the closest planet, has the fastest orbit around the Sun (88 Earth days).

So, size isn't the deciding factor:

While the hot environment near the Sun limited the size of the inner planets, it's not the sole reason for their proximity. The process of accretion and orbital mechanics played a much bigger role in determining where each planet ended up in our solar system.

Additional points:

There's no direct correlation between a planet's size and its distance from the Sun. For example, Jupiter, the largest planet, is much farther out than the smaller Mercury.

Studying the composition and formation of planets helps us understand the history of our solar system and the potential existence of planets in other star systems.