Q1: In a binary liquid system, the composition expressed as __________ is independent of the temperature & pressure.

ANS:D - all (a), (b) & (c)

(a) kg of solute/kg of solvent: This ratio represents the mass of solute per unit mass of solvent. However, this composition is dependent on temperature and pressure because changes in temperature and pressure can affect the densities of both solute and solvent, thus altering the ratio. (b) kg-mole of solute/kg-mole of solvent: This ratio represents the number of moles of solute per unit number of moles of solvent. Since it's expressed in terms of moles, which are independent of temperature and pressure, this composition remains constant regardless of changes in temperature and pressure. (c) kg-mole of solute/1000 kg of solvent: This ratio also represents the number of moles of solute per unit number of moles of solvent, but it's scaled to a standard quantity of solvent (1000 kg). Similar to option (b), since it's expressed in terms of moles, it remains constant regardless of changes in temperature and pressure. Therefore, options (b) and (c) are both independent of temperature and pressure because they are expressed in terms of moles, which are independent of these factors.