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

Give two important uses of washing soda and baking soda.

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

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

Write word equations and then balanced equations for the reaction taking place when -

$(a)$ dilute sulphuric acid reacts with aluminium powder.

$(b)$ dilute hydrochloric acid reacts with iron filings.

Five solutions $A,\,B,\,C,\,D$ and $E$ when tested with universal indicator showed $pH$ as $4,\,1,\,11,\,7$ and $9$, respectively. Which solution is

$(a)$ neutral ?

$(b)$ strongly alkaline ?

$(c)$ strongly acidic ?

$(d)$ weakly acidic ?

$(e)$ weakly alkaline ?

Arrange the $pH$ in increasing order of hydrogen-ion concentration.