Question

explain why the seeds be sown at right spacing

Answer 1

Seeds should be sown at right spacing because they need space to grow properly.
If they are crowded at one place then they will not be able to get sufficient sunshine minerals and water required for growth.

Answer 2

The plants should be grown in right spacing as they need more space for growing
If all the pleants are at same place the water that is poured to this plant may be absorbed by other plants.
Then the plant would not get proper sunlight,water and minerals.
Hope it helps