You see a twig floating under a bridge. You assume that wood is less dense than water and any twigs you throw into the water above the point that you saw will also travel
under the bridge. After throwing 100 twigs 99 twigs float under the bridge. 1
strangely sank. You make the conclusion that twigs are lighter than water and that
they are carried under the bridge by floating. This is known as a(n)
(2
words)

correct answer is option a.

tropopause, stratopause and mesopause have all in common aspect that is point of maximum temperature in its layer of the atmosphere. all layers of atmosphere observe abrupt change in temperature. tropopause is the boundary between troposphere and stratosphere. stratopause is the boundary between stratosphere and mesosphere. mesopause is the boundary between mesosphere and thermosphere. these all boundaries are ranges between altitude of 0 to 80 km.

the earth is thought to have been formed about 4.6 billion years ago by collisions from a cloud of hydrogen, helium, rock, ice and other materials. these were pulled together by gravity to form objects in and around earth like- asteroids and small early planets called planetesimals.

so, the best possible answer to this question will be option d- to harden materials to form different parts of earth’s layers