Determination of ash content of coal during its proximate analysis, the temperature of weighed coal sample is raised to 400 - 500°C in half an hour and maintained at the same level for further half an hour. The temperature is then raised to . . . . . . . . °C at which the sample is heated for one more hour before weighing it.

A. 775 ± 25

B. 875 ± 25

C. 975 ± 25

D. 1075 ± 25

Answer: Option A