________ process is used for producing soda ash?

Mannheim furnace is used in the manufacture of________?

During its calorific value determination by bomb calorimeter, coal is combusted by ________?

Boundary layer separation occurs when the________?

Presence of force moisture in coal is most disadvantageous during its ________?

The amount of a radioisotope remaining undecayed after a time equal to four times its half life, will be ________ percent?