Parts per Million, Mole Fraction — Prelims Questions

A $250\,\text{mL}$ sample of water contains $1.5\,\text{mg}$ of fluoride ions. Assuming the density of water is $1\,\text{g/mL}$, what is the concentration of fluoride ions in PPM?

A solution contains $180\,\text{g}$ of glucose ($\text{C}_6\text{H}_{12}\text{O}_6$, Molar mass = $180\,\text{g/mol}$) and $72\,\text{g}$ of water ($\text{H}_2\text{O}$, Molar mass = $18\,\text{g/mol}$). What is the mole fraction of glucose in the solution?

Which of the following statements about mole fraction is INCORRECT?

A solution has a concentration of $0.005\%$ by mass. What is its concentration in Parts per Million (PPM)?

A gas mixture contains $2\,\text{mol}$ of nitrogen ($\text{N}_2$) and $8\,\text{mol}$ of oxygen ($\text{O}_2$). If the total pressure of the mixture is $5\,\text{atm}$, what is the partial pressure of nitrogen?

A solution is prepared by dissolving $1.71\,\text{g}$ of sucrose ($\text{C}_{12}\text{H}_{22}\text{O}_{11}$, Molar mass = $342\,\text{g/mol}$) in $100\,\text{g}$ of water ($\text{H}_2\text{O}$, Molar mass = $18\,\text{g/mol}$). What is the mole fraction of sucrose in the solution?