Correct Option
The correct option is 2 only
Explanation
A nebula is a giant cloud of dust and gas in space. It serves as the primary raw material for the formation of stars. The process of star formation involves the gravitational collapse of these interstellar clouds.
Statement-wise Analysis
- Statement 1 is Incorrect: A nebula is primarily composed of hydrogen gas, along with helium and traces of other heavier elements and dust. It acts as a "stellar nursery" where new stars are born.
- Statement 2 is Correct: The gas within a nebula is not uniformly distributed. Due to gravitational forces, the nebula develops localized lumps or clumps of gas. If the distribution were perfectly uniform, gravitational collapse required for star formation would be difficult to initiate.
- Statement 3 is Incorrect: These localized clumps do not dissipate into the surrounding space. Instead, they grow into denser gaseous bodies under the influence of gravity. As these clumps become sufficiently dense and hot, they eventually ignite nuclear fusion, giving rise to stars.
Key Takeaway
Nebulae are interstellar clouds dominated by hydrogen gas. Star formation occurs through the gravitational collapse of localized clumps within these clouds, which grow denser to form stars rather than dissipating.