Q.50 mL of an aqueous solution of glucose $C_6H_{12}O_6$ (Molar mass: 180 g/mol) contains $6.02 \times 10^{22}$ molecules. The concentration of the solution will be (A) 0.1 M (B) 0.2 M (C) 1.0 M (D) 2.0 M

Concentration expresses how much solute is present relative to solvent or total solution, and this chapter's formulas draw on several distinct units, each suited to a different situation. Molarity (M) is moles of solute per litre (dm3) of SOLUTION -- convenient for everyday use, but technically temperature-dependent, since solution volume itself expands or contracts slightly with temperature; molarity is the unit used for osmotic pressure ($\pi=MRT$), since osmotic pressure is always measured at one fixed temperature. Molality (m) is moles of solute per KILOGRAM of SOLVENT -- because mass, unlike volume, is unaffected by temperature, molality is temperature-independent, making it the correct unit whenever temperature itself is varying within a measurement, as in boiling point elevation ($\Delta T_b=K_bm$) and freezing point depression ($\Delta T_f=K_fm$). Mole fraction ($x$) is the ratio of one component's moles to the TOTAL moles of all compo …