The cofficient of performance of a refrigerator is 5. If the temperature inside freezer is `-20^(@)C`, the temperature of the surroundings to which it rejects heat is :

Options

A. `41^(@)` C
B. `11^(@)` C
C. `21^(@)` C
D. `31^(@)` C

Answer

D

Explanation

Coefficient of performance,
Cop `=T_(2)/(T_(1)-T_(2)), 5 = (273 - 20)/(T_(1) - (273 - 20)) = 253/(T_(1) - 253)`
`5T_(1) - (5 xx 253) = 253`
`5T_(1) = 253 + (5 xx 253) = 1518`
`therefore T_(1) = 1518/5 = 303.6` or `T_(1) = 303.6 - 273 = 30.6 ~= 31^(@)` C