At the end of the words it could be c, k , ck or ke for /k/ sound.
When the word contains a short vowel, it will end with CK. Here are a few examples: DUCK, STUCK, DOCK, SOCK, CLICK, FLICK, SACK.
When the word contains a long vowel, it ends with KE. Here are a few examples: DUKE, PUKE, POKE, BLOKE, TAKE, MAKE, BIKE, LIKE.
We use C at the end of a word with 2 or more syllables. Think PICNIC, LOGIC, ARCTIC, COSMIC, DYNAMIC, ATHLETIC
We use K at the end of a word when it contains a vowel digraph (a double vowel). BOOK, LOOK, COOK, SEEK, CHEEK, MEEK, CREEK, GREEK.