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 : addition 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}

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

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

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 real roots of x + 1 = 0

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