To work as a control transformer

To work as a variable transformer

To work as a distribution transformer

To work as an isolating transformer

increase output power

increase output voltage

increase output current

none of these

an air-tight metallic drum fixed at the top of the oil-tank

an air-tight metallic drum fixed at the bottom of the oil-tank

overload protection device

none of these

is a high voltage winding

is a low voltage winding

may be low or high voltage winding

the two types of windings are placed in a sandwich manner

sulpher

alkali

moisture

all the above