What will be the molar mass of the dibasic acid if $1.575\mathrm{ }\mathrm{g}$ of a dibasic acid is neutralized by $25\mathrm{ }\mathrm{mL}$ of $1\mathrm{ }\mathrm{M}\mathrm{ }\mathrm{NaOH}$ solution.?

Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R).

Assertion (A) : An aqueous solution of $\mathrm{KOH}$ when for volumetric analysis, its concentration should be checked before the use.

Reason (R) : On aging,$\mathrm{KOH}$ solution absorbs atmospheric ${\mathrm{CO}}_2$.

In the light of the above statements, choose the correct answer from the options given below.

The titration curve of weak acid vs. strong base with phenolphthalein as indicator is shown below. The ${\mathrm{K}}_{\text{phenolphthalein }}=4\times {10}^{-10}$

Given: $\log 2 = 0.3$

The number of following statement/s which is/are correct about phenolphthalein is _______

A. It can be used as an indicator for the titration of weak acid with weak base.

B. It begins to change colour at $\mathrm{pH} = 8.4$

C. It is a weak organic base

D. It is colourless in acidic medium

$20 \mathrm{mL}$ of $0.02 \mathrm{M}$ hypo solution is used for the titration of $10 \mathrm{mL}$ of copper sulphate solution, in the presence of excess of $\mathrm{KI}$ using starch as an indicator. The molarity of ${\mathrm{Cu}}^{2+}$ is found to be $\_\_\_\_\_\times {10}^{-2}\mathrm{M}$ (nearest integer)

Given : $$\begin{gathered} 2{\mathrm{Cu}}^{2+}+4{\mathrm{I}}^{-}\to {\mathrm{Cu}}_2{\mathrm{I}}_2+{\mathrm{I}}_2 \\ {\mathrm{I}}_2 + 2{\mathrm{S}}_2{\mathrm{O}}_3^{-2} \to 2{\mathrm{I}}^{—} + {\mathrm{S}}_4{\mathrm{O}}_6^{-2} \end{gathered}$$