How long should the assignment answers be For 20 or 25 marks?

It primarily depends on the course that you are pursuing (BA, BSC, BCA, BCOM, etc). IGNOU prioritizes quality over quantity. As a result, it is best to write as much as possible in a direct and concise manner. A4 sheets are preferred.

It is recommended to write half a page for a 5-mark answer.

Write the answer in full page for 10 points

2 pages for a 20-mark question (front & back)

For a 25-point question, two or two and a half would suffice.

This is how the answer writing pattern is divided which would fetch you marks if you have written on point.