A. Only one word ends in sede:

1. supersede

B. Only three words end in ceed.

1. exceed

2. proceed

3. succeed

Note. however that derivatives of these three words are spelled with only one e:

1. excess

2. procedure

3. success

C. All other words ending with the sound of "seed" are spelled cede.

1. precede	3. secede	5. recede
2. concede	4. intercede	6. accede