You can use the following forms:
"whether is .."
is used to introduce one alternative ."
"We should find out whether the museum is open."
"whether is or not "
is used to introduce an indirect question,when one doesn't know which of 2 alternatives is true.
" He was not certain whether his friend was there or not."
"whether .. or not "
if on the one hand…or even if on the other hand
"You'll eat that, whether you like it or not."