Is the k only silent consonant?

No, "k" is not the only silent consonant in English. There are many silent consonants in English, depending on the word and its origin. Here are some examples:

Silent "k":

* Knife, know, knee

Silent "b":

* Debt, doubt, lamb

Silent "g":

* Gnat, gnome, sign

Silent "h":

* Hour, honest, heir

Silent "l":

* Calm, could, walk

Silent "w":

* Write, wrist, wrong

Silent "t":

* Listen, castle, often

Silent "e":

* Write, have, give

Silent "c":

* Indict, scissors, yacht

This is not an exhaustive list, as there are many other examples of silent consonants in English.

It's important to remember that the pronunciation of words can vary depending on their origin, historical changes, and regional dialects.