Why is किसको पढ़ना नहीं है not correct?
This sounds unnatural. नहीं should come before the verb.
yeah, why can't it be "किसको पढ़ना नहीं है"
Is किसे correct as well? किसे is short for किस को (like उसे is short for उसको)
कौन - किस |Differences?
I think that किस is the oblique form of कोन, which means that it must be used for example when it is followed by a postposition.
It can also mean "Who doesn't want to study?" if your teacher asks you this in the class. But it can only in rare situations mean what the solution is