name the following binary acids.

Question

is the name for K2S, potassium sulphide or potassium sulfide?

and is the name for K2Te, potassium telluride?

Answer 1

K2Te is correct.
For K2S it is potassium sulfide in the U.S. It has long been potassium sulphide in the UK but my understanding is that there is a concerted effort to change that in the UK to the "american" spelling. I am from the U. S. so I can't speak for an official opinion in the UK.