The words with c present the following spelling rules for writing:
The verbs ending in -cer or -cir (except for the verb sew, cough, grab). For example: to know, to redden, to make, to rock, to say, to darn, to seduce.
The words ending in -cient. For example: insufficient, growing, patient, omniscient, sufficient.
The words ending in -science. For example: patience, conscience, insufficiency.
The words ending in -foundation. For example: knowledge, supply, empowerment, birth
The words ending in -icide. For example: parricide, genocidal.
The words ending in -acidic, -aceous. For example: olive, opiate, orchid, blond, herbaceous, greyish
The words ending in -ancio, -ancia. For example: tiredness, elegance, fortune telling, bulge.
The words ending in -encio, -encia. For example: agency, ambivalence, clemency, essence, evidence, laurencio, silence, solvency
The nouns ending in -tion. For example: provision, voting, falsification, condition, warning.
They are written with double c (cc) the words in whose lexical family there is a word that contains the string