I believe the answer is two convex lenses. A compound microscope has two systems of lenses for greater magnification, the ocular, or eyepiece lens that one looks into and the objective lens, or the lens closest to the object. Both the ocular lens and the objective lens are convex lens.
Answer: The differences between terrestrial planets and the giant planets are s follows-
- The inner planets namely Mercury, Venus, Earth and Mars are the terrestrial planets, whereas the outer planets namely Jupiter, Saturn, Uranus and Neptune are known as the outer planets.
- Inner planets are composed mainly of silicate materials as well as some metals, whereas the giant planets are comprised of water (in different states) and gases such as Hydrogen and Helium.
- The density of the inner planets are more in comparison to the outer planets, where earth has the highest of about 5.5 gm/cm³ and Saturn has the lowest of about 0.7 gm/cm³.
- Due to the location of the inner planets near to the sun, they have high boiling point, whereas outer planets are much far from the sun so they have a low boiling point.
Answer: A.
Explanation: Roughly 180 - 200 million years ago, just before the first dinosaurs evolved. Mammals themselves evolved from a group or reptiles which exhibited mammal-like traits. One of them was specialized teeth. Reptiles tend to have teeth all the same shape. The mammal-like reptiles evolved tiny teeth in front of the jaw and two pairs of over sized fangs along the the sides. Like modern mammals, the head was large in proportion to the rest of the body. The jaws were also evolving another mammal trait, the ability to move sideways. Despite the lack of specialized teeth, acute hearing and the ability to chew, the dinosaurs evolved an adaptation which made them far more successful than mammals--modified leg bones. These limbs could be articulated directly under their bodies. This enabled the legs to support more weight, since the limbs were now under the body instead of at the sides. Then dinosaurs did something which secured their dominance for the next 120 million years - they began to stand on two legs. Although the back was still parallel to the ground, running on two legs greatly increased the dinosaur's speed. Mammals could simply not compete with swift, giant predators and were forced to remain small, and most became nocturnal to evade dinosaurs which were probably active during the day. Despite that they managed to survive which allowed the further evolution of mammals into us, humans.
