The temperature of food material in refrigerator is 4$$^\circ$$C and temperature of environment is 15$$^\circ$$C. If carnot cycle is used in its working gas, then find its carnot efficiency.

If $$7 \mathrm{~gm} \mathrm{~N}_2$$ is mixed with $$20 \mathrm{~gm} \mathrm{~Ar}$$, there $$\frac{C_p}{C_V}$$ of mixture will be

In an isobaric process, the work done by a di-atomic gas is 10 J, the heat given to the gas will be

Calculate radiation power for sphere whose temperature is 227$$^\circ$$C, radius 2 m and emissivity 0.8.