I think it would be penicillin as it saved many lives in its time and ours.
Light energy into chemical energy
Answer:
See below.
Explanation:
Aqueous copper chloride reacts with sodium hydroxide aqueous solution to give a precipitate (solid) of copper hydroxide and aqueous sodium chloride.
A solution is turning blue means, it is turning it's behavior to Basic from Acidic. Reagent D must be a Basic component so it is increasing the pH of the solution. As reaction does not depend on the phase of the component, it could be anything i.e., Solid, Liquid or gas.
Hope this helps!
