1. The problem statement, all variables and given/known data I've been asked to find out if are entangled states or not 2. Relevant equations I thought an entangled state was one where a measurement of one qubit revealed the nature of the other qubit in the state 3. The attempt at a solution If I am correct in my definition of an entangled state then a) and b) are entangled as measuring a 1 or a zero in a) reveals the state of the 2nd qubit, and there is only one type of qubit in b). c isn't entangled as measurement of q1 does not reveal the nature of q2? Could someone please tell me if I am correct or not, and if not why not? Many thanks!