State which of the following sets are closed under the operation : addition `R,Z,N,Q,W,C,R-{0}`

State which of the following sets are closed under the operation : division R,Z,N,Q,W,C,R-{0}

State which of the following sets are closed under the operation : subtraction R,Z,N,Q,W,C,R-{0}

State which of the following sets are closed under the operation : multiplication R,Z,N,Q,W,C,R-{0}

State whether the following sets are null set or singleton set: {x|x in R,x!=x}

State whether the following sets are null set or singleton set: {x|x in R,x^2=-4}

State which of the following sets are null set or singleton set:the set of Indian medalists in 1996 Olympic

Is the set of integers closed under the operation of Division? Give examples

State which of the following sets are null set or singleton set:the set of deserts in the Himalayan range

State which of the following sets are null set or singleton set:the set of positive odd integers less than 3

State which of the following sets are null set or singleton set:the set of real roots of x + 1 = 0