1. why do cations move towards cathode and anions move towards anode?
2. what is the ratiobetween hydrogen and oxygen from water by volume

1. Cations are positively charged ions and anode are negatively charged ions. On the other hand cathode is negatively charged electrode, and anode is positively charged electrode. We know unlike charges attract. So, cations being positively charged move towards the negative electrode that is cathode, and anions being negatively charged move toward the positive electrode that is anode.

2. Ratio between hydrogen and oxygen in water (H₂O)  in terms of volume is 2:1 (Because in H₂O there are 2 atoms of hydrogen and 1 atom of oxygen)

Hope this helps!!