Is there any object or phenomena on which only one force is acting? In a simple manner I want to know the examples on which only one force is acting.

This is homework. Based on your textbook you read... what do you think the answer is and why? We will help you with your assignment but we will not do it for you.

Read Newton's 3rd law.

Third law "To every action there is always an equal and opposite reaction." I think is that on earth everything experiences minimum 2 force at a time that is gravitational and one which is simply opposite to it. I am confused! I don't think that there's anything which which experience single force.

There are no examples. 3rd law.

Force always occurs in pair. Does't it? Thank you so much!