Assertion: One molar aqueous solution always has a higher concentration than one molal solution.
Reason: One molar solution contains less solvent than 1 molal solution.
Answer & explanation
Correct answer: option 1
The correct answer is option 1. Both assertion and Reason are correct, and the reason is the correct explanation of the assertion.
One molar aqueous solution is more concentrated than 1 molal aqueous solution because 1 molar solution contain 1 mole of solute in 1 litre of the solution which include both solute and solvent. So, the mass of solvent (i.e. water) is less than 1000 gram. Therefore 1 molar aqueous solution contains 1 mole of solute in less than 1000 gram of solvent whereas 1 molal solution has 1 mole of solute in 1000 gram of solvent. Hence concentration will be more in 1 molar aqueous solution.