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
Out of 900 reported species of living gymnosperms, conifers are represented by about 500 species, About 2,50,000 species of angiosperms (flowering plants) have also been reported in the world. The vast and dominant woodlands in Europe, Asia, North America and mountains such as Himalayas are wooded with
Options: all gymnosperms, except conifers, only angiosperms, only conifers, angiosperms and all gymnosperms except conifers
Sound produced at a point is heard by a person after 5 second, while the same sound is heard by another person after 6 seconds. If the speed of sound is 300 m/s, what could be the maximum and minimum distances between the two persons?
Options: 1.8 km, 0.15 km, 2.2 km, 0.20 km, 2.8 km, 0.25 km, 3.3 km, 0.30 km