How many atoms are present in a (i) H2S molecule and (ii) PO43- ion

Ans: Hydrogen sulphide has a structure similar to that of water. There are three atoms in total in an H2S molecule. Two of the three elements are hydrogen, and one is sulphur. 

• PO43- is a phosphoric acid derivative with the chemical name Phosphate. There are five atoms in total in a PO43- ion. One of the five atoms is phosphorus, and the other four are oxygen.