Question

1)Electrolysis of water gives hydrogen and oxygen.
2)A bulb glows when electricity is passed through it.
Explain that these are which type of changes (physical or chemical)

Answer 1

Answer is in short form now
1.

In pure water at the negatively charged cathode, a reduction reaction takes place, with electrons (e−) from the cathode being given to hydrogen cations to form hydrogen gas. The half reaction, balanced with acid, is:

Reduction at cathode: 2 H+(aq) + 2e− → H2(g)
At the positively charged anode, an oxidation reaction occurs, generating oxygen gas and giving electrons to the anode to complete thecircuit:
Oxidation at anode: 2 H2O(l) → O2(g) + 4 H+(aq) + 4e−
Cathode (reduction): 2 H2O(l) + 2e− → H2(g) + 2 OH−(aq)
Anode (oxidation): 4 OH−(aq) → O2(g) + 2 H2O(l) + 4 e−
Combining either half reaction pair yields the same overall decomposition of water into oxygen and hydrogen:
2.
I think your question is, "Why does a bulb glow when electric current passes through it?"
when the thin filament carries current through it, it heats up to high temperatures to give light output.
In a "standard" 75 or 100 watt 120 volt bulb, the filament temperature is roughly 2550 degrees Celsius, or roughly 4600 degrees Fahrenheit. At high temperatures like this, the thermal radiation from the filament includes a significant amount of visible light.

This is the correct answer.