The stoichiometric reaction of $516 \ g$ of dimethyldichlorosilane with water results in a tetrameric cyclic product $X$ in $75 \%$ yield. The weight (in $g$) of $X$ obtained is. . . . . . . [Use,molar mass $(g \ mol^{-1})$: $H=1, C=12, O=16, Si=28, Cl=35.5$]

Phosphoric acid $(H_3PO_4)$ is a tribasic acid and one of its salts is sodium dihydrogen phosphate $(NaH_2PO_4)$. What volume of $1 \ M$ $NaOH$ solution should be added to $12 \ g$ of sodium dihydrogen phosphate (mol. wt. $120$) to exactly convert it into trisodium phosphate $(Na_3PO_4)$? (Answer in $mL$)

Hardness of water is $200 \ ppm$. Calculate the molarity and normality of $CaCO_3$ in the water.

If $20 \ mL$ of $0.4 \ N \ NaOH$ solution completely neutralises $40 \ mL$ of a dibasic acid,the molarity of the acid solution is $.......... \ M$.

If $5.85 \ g$ of sodium chloride is added to water to make a $500 \ mL$ solution,what is the molarity of the sodium chloride solution (in $M$)? (Molar mass $= 58.5 \ g/mol$)

How many grams of $3-$hydroxypropanal $(MW=74)$ must be dehydrated to produce $7.8 \ g$ of acrolein $(MW=56)$ $(C_3H_4O)$ if the percentage yield is $64\%$? (Round off to the nearest integer).
[Given: Atomic masses: $C = 12.0 \ u, H = 1.0 \ u, O = 16.0 \ u$]