Question

The fusion reaction in sun started:

• A. 1 million years ago
• B. 100 million years ago
• C. 2.5 billion years ago
• D. 1 billion years ago

Answer 1

The correct option is C

2.5 billion years ago

1. Sun formed 2.5 billion years ago from a giant spinning cloud of hydrogen gas.
2. Strong gravitational force squeezed hydrogen gas in small volume known as the core of sun.
3. As a result, light nuclei of hydrogen fuse together to form a helium nucleus and vast amount of energy released.

Hence option C is the correct answer.