Questions & Answers about Мой кот лежит на диване и мурлычет.
Because кот is a masculine singular noun, and мой has to agree with it.
In Russian, possessive words like мой change for gender, number, and case:
- мой кот = my cat, masculine
- моя кошка = my cat, feminine
- моё окно = my window, neuter
- мои коты = my cats, plural
Here, кот is masculine, so мой is the correct form.
Strictly speaking, кот usually means a male cat.
Compare:
- кот = male cat / tomcat
- кошка = female cat
- кошка can also sometimes be used more generally for cat as a species
So мой кот suggests that the speaker has a male cat. If the cat were female, you would normally say моя кошка.