Why should curd and sour substances not be kept in brass and copper vessels ?

Give two important uses of washing soda and baking soda.

$10 \,mL$ of a solution of $NaOH$ is found to be completely neutralised by $8 \,mL$ of a given solution of $HCl$. If we take $20 \,mL$ of the same solution of $NaOH$, the amount of $HCl$ solution (the same solution as before) required to neutralise it will be …… $mL$

Fresh milk has a $pH$ of $6$. How do you think the $pH$ will change as it turns into curd ? Explain your answer.

You have two solutions, $A$ and $B$. The $pH$ of solution $A$ is $6$ and $pH$ of solution $B$ is $8$. Which solution has more hydrogen ion concentration Which of this is acidic and which one is basic?