$A$ solution turns red litmus blue,its $pH$ is likely to be

$A$ milkman adds a very small amount of baking soda to fresh milk.
$(a)$ Why does he shift the $pH$ of the fresh milk from $6$ to slightly alkaline?
$(b)$ Why does this milk take a long time to set as curd?

Plaster of Paris should be stored in a moisture-proof container. Explain why?

Name the sodium compound which is used for softening hard water.

Name the substance which on treatment with chlorine yields bleaching powder.

What is a neutralization reaction? Give two examples.