What type of solution is obtained from an amalgam of mercury with sodium?

The molarity of the solution obtained by mixing $50 \ mL$ of concentrated $H_2SO_4$ $(36 \ N)$ with $50 \ mL$ of water is .......... $M$.

$50 \ mL$ of an aqueous solution of glucose contains $6.02 \times 10^{22}$ molecules. The concentration of the solution is? ........... $M$

The mole fraction of urea in an aqueous urea solution containing $900 \text{ g}$ of water is $0.05$. If the density of the solution is $1.2 \text{ g cm}^{-3}$,the molarity of the urea solution is . . . . . (Given data: Molar masses of urea and water are $60 \text{ g mol}^{-1}$ and $18 \text{ g mol}^{-1}$,respectively)

The molality of a solution containing $15.20 \ g$ of urea (molar mass = $60 \ g \ mol^{-1}$) dissolved in $150 \ g$ of water is:

The density of $3 \ M$ solution of $NaCl$ is $1.0 \ g \ mL^{-1}$. Molality of the solution is $...... \times 10^{-2} \ m$. (Nearest integer). Given: Molar mass of $Na$ and $Cl$ is $23$ and $35.5 \ g \ mol^{-1}$ respectively.