What is molarity?

The molar concentration of chloride ions in the resulting solution of $300 \ mL$ of $3.0 \ M$ $NaCl$ and $200 \ mL$ of $4.0 \ M$ $BaCl_{2}$ will be (in $M$)

If $23 \ g$ of ethanol ($C_2H_5OH$,molar mass $= 46 \ g \ mol^{-1}$) is dissolved in $500 \ mL$ of solution,find the molarity of the solution in $M$.

$A$ sample of drinking water is found to be severely contaminated with chloroform $(CHCl_3)$,which is a suspected carcinogen. The level of contamination is $15 \ ppm$ (by mass). Calculate the molarity of chloroform in the water sample.

Molarity $(M)$ of an aqueous solution containing $x \ g$ of anhydrous $CuSO_4$ in $500 \ mL$ solution at $32^{\circ} C$ is $2 \times 10^{-1} \ M$. Its molality will be. . . . . .$\times 10^{-3} \ m$ (nearest integer). [Given density of the solution $= 1.25 \ g/mL$.]

Which of the following statements is true?
$(1)$ $200 \ mL$ of $0.2 \ M \ NaOH$ has the same number of moles of solute as $1000 \ mL$ of $1 \ M \ NaOH$.
$(2)$ $200 \ mL$ of $1 \ M \ NaOH$ has the same number of moles as $1000 \ mL$ of $0.2 \ M \ NaOH$.
$(3)$ $100 \ mL$ of $0.2 \ M \ NaOH$ has the same number of moles as $1000 \ mL$ of $1 \ M \ NaOH$.
$(4)$ $2000 \ mL$ of $0.2 \ M \ NaOH$ has the same number of moles as $1000 \ mL$ of $1 \ M \ NaOH$.