Reasoning

Seat, rung, and leg are all parts of a chair. Not all chairs have cushions.

All except Veil cover the head, while veil covers the face.

All except Mango have more than one seed.

All except Rice are rabi crops, while rice is a kharif crop.

In all other pairs, lack of first causes the second.

All except Appendix are bones, while appendix is an organ.