Explanation: Among two-high rolling mill, cluster rolling mill, separation rolling mill and tandem rolling mill. Separation rolling mill is not a type of rolling mills.

Explanation: In two high rolling mill, the direction of both the rollers is opposite to one another. Hence, one clockwise while other anti-clockwise.

Explanation: In two high rolling mill, if the direction of the roller is reversed, then that system is called as, two high reversing mill.

Explanation: In three high rolling mill, the direction of the rollers in the top and bottom are the same, and the direction of the roller in the middle is opposite to the two.

Explanation: In four high rolling mill, there are four rolls employed for roliing. The direction of two rollers is the same and the remaining two rollers roll in opposite directions.

Explanation: The shape and the cross section shape of the billet, which is desired is not obtained in one single pass. One may have to use multiple pass to achieve desired cross section shape.

Explanation: When a rolled stack is made, there is an improvement seen in the physical properties of the material, it does not affect the boiling point of the material.

Explanation: Rolling is very useful for making articles like bars, plates and rails, but it cannot be used for making helmets. For making helmets, different methods of casting are used.

Explanation: The material ingot is known for sustaining high temperature and heat conditions. Before the process begins, the ingot is fired using gas and brought up to a temperature of 1200°C.

Explanation: In hot rolling process, the velocity of material at entry is lower than the velocity at exit.