From the following, choose the set in which names of Secretary-Generals of the UNO are arranged in correct chronological order?
Options: U Thant, Kurt Waldheim, Dag Hammarskjoeld, Trygve Lie., Trygve Lie, Dag Hammarskjoeld, U Thant, Kurt Waldheim., Trygve Lie, U Thant , Dag Hammarskjoeld, Kurt Waldheim., U Thant, Dag Hammarskjoeld, Trygve Lie, Kurt Waldheim.
Options: the densities of the liquid in the two vessels are equal, the level of the liquid in the two vessels are at the same height, both its limbs are of unequal length, the temperature of the liquids in the two vessels are the same
It is easier to roll a barrel full of coal tar than to pull it because
Options: the full weight of the barrel comes into play when it is pulled, the rolling friction is much less than the sliding friction, more surface area of the barrel is in contact with the road when it is pulled, coal tar is a liquid and it flows in the barrel when it is rolled