Calculate the mole fraction of the solute in each of the following solutions:

1. a solution containing 75 g of ethanol (C.H.O) in 450 g of water

2. a 20% aqueous hydrochloric acid solution

3. a solution containing 2.6 g of sodium sulfate in 0.020 k g of water

4. a 40% solution of phenol (C.H.O) in benzene (CH₂)​