The concentration of $1 \ L$ of $CaCO_3$ solution is $1000 \ ppm$. What is its concentration in $mol \ L^{-1}$ ?
$(Ca=40 \ u, O=16 \ u, C=12 \ u)$

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

An aqueous solution of alcohol contains $18 \ g$ of water and $414 \ g$ of ethyl alcohol. The mole fraction of water is

Which of the following is dependent on temperature $?$

Which of the following statements is correct?
$(1)$ Molarity is the number of moles of solute in one liter of solution.
$(2)$ The normality and molarity of a sodium carbonate solution are the same.
$(3)$ The number of moles of solute dissolved in $1000 \ g$ of solvent is defined as molality $(m)$.
$(4)$ The ratio of the mole fractions of solute and solvent is equal to the ratio of their respective moles.

The approximate molarity of a solution in $mol \ L^{-1}$ that contains $13.50 \ g$ of $NaCl$ dissolved in $452 \ mL$ of water is