He is seated in/on the chair.

He is seated in the chair.

He sat down on the chair.

Thanks, Region.

What is the difference in meaning between the pair of sentences?

He sat on the chair.
He sat in the chair.

Do the above sentences mean the same as the first pair? Which pair is more commonly used?

We sit on a hard basic chair or stool; we sit in a large comfortable chair such as an armchair.

Thanks, contrex.

He sat on the chair.
He sat in the chair.

He was seated in the chair.
He was seated on the chair.

Which pair of sentences is more commonly used?

They mean different things. Sat tells of an action; seated tells of a state.

Thanks, Region and contrex.