Ahomogeneous mixture consists of 34% ethanol and 66% isopropanol. which of these is the solute of the mixture?

The solute is ethanol. This is a matter of looking at the definition of solute. Solute - The minor component in a solution. What's dissolved in the solvent. With that definition in mind, the answer is pretty obvious. The solute is the 34% ethanol. It loses on any basis you can imagine for comparison. Percentage wise it's about half that of the isopropanol. Their densities are almost identical 789 kg/m^3 vs 786 kg/m^3, so there's still almost twice as much isopropanol as ethanol by mass.

The stars twinkle in the night sky because of the effects of our atmosphere. When starlight enters our atmosphere it is affected by winds in the atmosphere and by areas with different temperatures and densities. This causes the light from the star to twinkle when seen from the ground