Question

how can you get Oxygen and hydrogen from water?

plz describe it in long sentences

Answer 1

It could be done by electrolysis process ...

H2O gives...H2 + O2 oxygen gas is obtained at anode and hydrogen gas at cathode

Answer 2

Tape wires to each pole of a battery. Dunk both wires in salt water (not touching each other). That's it.

You'll notice bubbles forming on each wire, the wire connected to the negative terminal will form hydrogen gas and the one connected to the positive terminal will form oxygen gas. You'll also get some chlorine gas on the positive wire, so you might want to do this in a well-ventilated area. If you're just using a single AA battery (or equivalent) the production of gas is going to be pretty slow, but that's the simplest way to do it.

There are more complex chemical methods to perform this separation, but this is the easiest to do with commonly available equipment.

OR
OR
While electrolysis works it is extremely inefficient (39 kWh per kg of hydrogen)… unless you need hydrogen for a specific reason like rocket fuel, making potato chips (hydrogenated oils … big consumer of hydrogen) or industrial metal processing, you are almost always better off using the electricity instead of the hydrogen for energy. In the proposed hydrogen economy the reality of this derailed the vision. You are far better off with a battery powered car than a hydrogen powered car. the equivalent energy of a gallon of gas in a car using hydrogen would cost $25 a gallon due to the energy conversion cost.

The most economical way to make hydrogen is called steam methane reforming.