The ratio of heat accepted to the heat rejected by a carnot engine gives :

Explanation

The ratio of heat accepted to the heat rejected by a Carnot engine gives the efficiency of the working substance. A Carnot engine is a theoretical heat engine that operates on the reversible Carnot cycle. It consists of two isothermal and two adiabatic processes. The efficiency of a Carnot engine depends only on the temperatures of the hot and cold reservoirs, and is given by the Carnot efficiency formula: Efficiency = 1 - (Temperature of the cold reservoir / Temperature of the hot reservoir) The heat accepted is the heat energy absorbed by the engine from the hot reservoir, and the heat rejected is the heat energy expelled by the engine to the cold reservoir. The ratio of heat accepted to heat rejected is equal to the ratio of the absolute temperatures of the hot and cold reservoirs. Therefore, we can rewrite the Carnot efficiency formula as: Efficiency = 1 - (Temperature of the cold reservoir / Temperature of the hot reservoir) Efficiency = 1 - (Heat rejected / Heat accepted) So, the ratio of heat accepted to heat rejected by a Carnot engine gives the efficiency of the working substance. Therefore, the correct option is (a) - the ratio of heat accepted to heat rejected by a Carnot engine gives the efficiency of the working substance.