Who defined acid and base on the basis of chemical properties?

What will be the action of the following substances on litmus paper? Dry $HCl$ gas,Moistened $NH_3$ gas,Lemon juice,Carbonated soft drink,Curd,Soap solution.

State whether the following statement is true or false:
Acids produce $H_{3}O^{+}$ or $H^{+}(aq)$ ions in water.

State what happens when zinc granules are heated with sodium hydroxide solution. Write the balanced equation for this reaction. Name the main product formed in this reaction.

One of the constituents of baking powder is sodium hydrogencarbonate, the other constituent is

When soap is scrubbed on a stain of curry on a white cloth,why does it become reddish-brown,and why does it turn yellow again when the cloth is washed with plenty of water?