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 $= 58.5 \ g/mol$)

What is obtained when one mole of calcium phosphide is reacted with excess water?

What will be the volume of $O_2$ gas at $STP$ which is obtained by thermal decomposition of $30.62 \ g$ $KClO_3$,with $80\%$ purity?

$x$ grams of calcium carbonate was completely burnt in air. The weight of the solid residue formed is $28 \,g$. What is the value of $x$ (in grams)?

$5 \ g$ of $NaOH$ was dissolved in deionized water to prepare a $450 \ mL$ stock solution. What volume (in $mL$) of this solution would be required to prepare $500 \ mL$ of $0.1 \ M$ solution?
Given: Molar Mass of $Na$,$O$,and $H$ is $23$,$16$,and $1 \ g \ mol^{-1}$ respectively.

$100 \ mL$ of $0.1 \ N$ hypo solution is decolourised by the iodine liberated from the addition of $x \ g$ of crystalline copper sulphate to an excess of $KI$. The value of $x$ is ............. $g$ (molecular weight of $CuSO_4 \cdot 5H_2O$ is $250$).