A. In what layer can a hot-air balloon travel? B. Why can't a hot-air balloon go to higher layers?

The particles of the gas inside the ball heats up, bouncing off each other and spreading farther apart.hope my answer has you : )

If the heat engine is a perfect carnot cycle engine, thenefficiency = (t2-t1)/t2   where t1=temperature of cold reservoir ( ° k) = 135            t2=temperature of hot reservoir ( ° k)   = 325thereforeefficiency = (t2-t1)/t2 = (325-135)/325 = 0.5846 = 58%  note: this is the theoretical maximum efficiency of a perfect heat engine.   real-life engines do not achieve this value.

Iwould say earthquakes.