Question

Which one is a chemical change - electrolysis of water or sodium chloride exposed to sunlight

Answer 1

electrolysis of water

Answer 2

In first case, 
H₂O⇒ H₂+O₂
       Δ
In second:
NaCl (sunlight) ⇒ NaCl
                                  (no change)
Hence, first is the chemical change only.