Answer:
correct option: A. tetrahedral
Explanation:
when we talk about hydrogen bonding in water due to oxygen then need to check the number of lone pair available for hydrogen bonding because hydrogen bond form between lone pair of oxygen and hydrogen of other water molecule so there are two lone pair which forms hydrogen bond and there are also two other covalent bond with hydrogen of same molecule so total number is 4 it means they will form a tetrahedral geometry
Isotope - the same element, but different atomic mass so 1)35 Cl and 37 Cl
What your question for number 3
I think it might be A. i am not totally sure though