Which of the following statement is wrong?

Answer: Option D

Option A: The factor of evaporation for all boilers is always greater than unity

This statement is correct. The factor of evaporation is a measure of how much water a boiler can evaporate under certain conditions compared to a baseline. It is always greater than unity because it takes into account the sensible heat added to the water before it reaches the boiling point.

Option B: The amount of water evaporated in kg per kg of fuel burnt is called equivalent evaporation from and at 100°C

This statement is correct. Equivalent evaporation is a standardized way to compare the performance of boilers, considering the evaporation of water at 100°C under standard atmospheric pressure.

Option C: The ratio of heat actually used in producing the steam to the heat liberated in the furnace is called boiler efficiency

This statement is correct. Boiler efficiency is a measure of how effectively the heat produced in the furnace is transferred into the water to generate steam.

Option D: None of the above

This is the correct answer because none of the statements A, B, or C are wrong.