Which of the following contains oxalic acid?

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?

Under what soil condition do you think a farmer would treat the soil of his fields with quick lime $(CaO)$,slaked lime $(Ca(OH)_2)$,or chalk $(CaCO_3)$?

What happens when $CO_{2}$ is passed through lime water in excess?

According to the Bronsted-Lowry acid-base theory,the substance which donates a proton $(H^+)$ to another substance is called ............

How is the concentration of hydroxide ions $(OH^-)$ affected when excess base is dissolved in a solution of sodium hydroxide?