On a night when the sky is clear, the temperature may dip considerably; on a cloudy night the temperature will usually dip much less. The reason for this difference is that
Options: the clear sky allows radiant energy to escape readily from the earth, on a cloudy night the clouds are warm and therefore retard the cooling, the clear sky allows the cold of outer space to reach the earth, current of air carry the heat away from the earth on a clear night
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.