B. To orient themselves and to find food
Since they cannot see very well or even at all in some cases, these animals use echolocation instead to orient themselves, to find where they are, and to find food.
A little trick i learnt: The atomic number reflects how many electrons there are, and there must be an equal charge. therefore, there are the same amount of protons as there are electrons. so if it has 81 protons, we look for number 81 in the periodic table, Thallium
A. <span>Pollution made in one country might contaminate the ground, water, and air of other countries.</span>
