Correct Option
The correct option is 2 only
Explanation
The formation of stars and galaxies is rooted in the evolution of the early universe following the Big Bang. The uneven distribution of matter and energy in the early universe created the gravitational conditions necessary for the accumulation of gas and the subsequent birth of celestial bodies.
Statement-wise Analysis
- Statement 1 is Incorrect: In the early universe, the distribution of matter and energy was not even. These initial density differences gave rise to differences in gravitational forces. These forces caused matter to get drawn together, forming the basis for the development of galaxies.
- Statement 2 is Correct: A galaxy starts to form by the accumulation of hydrogen gas (not helium) in the form of a very large cloud called a nebula. While helium was present in the early universe, hydrogen is the primary element involved in the formation of nebulae and subsequent star formation.
- Statement 3 is Incorrect: The event believed to have taken place about 13.7 billion years ago is the Big Bang. The formation of stars is believed to have taken place much later, approximately 5 to 6 billion years ago.
Key Takeaway
Key Takeaway: The Big Bang occurred 13.7 billion years ago, while star formation began around 5-6 billion years ago. Nebulae, the birthplaces of stars, are primarily composed of hydrogen gas.