"Is it easy to play the violin?"
Translation:Keman çalmak kolay mı?
It is grammatically wrong. In Turkish there are three sets of infinitives;
-ma/-me -mak/-mek -ış/-iş
As you can see -ası/-esi isn't one of them. However, there are a lot of Turkish people who are using -ası/-esi as infinitive. So, even though it's not correct to say "Keman çalması kolay mıdır?", it is accepted.
I'm going to write three sets of verbals in Turkish;
Verb -> Infinitive -ma/me -mak/-mek -ış/-iş
Verb -> Participle -An -AsI -mAz -Ar -Dİk -EcEk -mIş
Verb -> Gerund -ken -alı -madan -ince -ip -arak -dıkça -e….-e -r…..-maz -casına -meksizin -dığında