Volume of the ethanol = 35 ml
Volume of the water = 65 ml
Volume percentage = \(\frac{\text { Volume of the solute }}{\text { Volume of the solution }} \times 100\)
Volume percentage =\(\frac{\text { Volume of the solute }}{\text { Volume of the solute + Volume of the solvent }} \times 100\) 
Volume percentage = \(\frac{35}{35+65}\times\)100
Volume percentage = \(\frac{35}{100 }\) x 100
= 35%

Amount of sodium nitrate dissolved in 100 g of water at 50°C is 114 g
\(\therefore\) Amount of sodium nitrate dissolving in 50 g of water at 50°C is = \(\frac{114\times50}{100}\)
= 57 g
Similarly amount of sodium nitrate dissolving in 50g of water at 30°C is = \(\frac{96 \times 50}{100}\)
= 48 g
Amount of sodium nitrate thrown when 50g of water is cooled from 50°C to 30°C is 
57 – 48 = 9 g

Mass of potassium chloride in 100 g of water in saturated solution = 37 g
Mass of potassium chloride in 60 g of water in saturated solution = \(\frac{37}{100}\)× 60
= 22.2 g

(i) Cool drinks give more fizz at the foot of mountain because the atmospheric pressure is less at the top of the mountain.
(ii) So the pressure affects the fizz of the cool drink.

(i) Vinu will get faster dissolution of sugar.
(ii) Temperature is one of the factors.
(iii) It will affect the solubility of a solute in a liquid.
(iv) Solvent increases with increase in temperature.