Three factors responsible for the rise of a new species: 1. Natural selection: Natural selection is the differential endurance and proliferation of individuals because of contrasts in phenotype. Natural selection can prompt speciation, where one species brings about another and unmistakably various species. It is one of the cycles that drive evolution and assists with clarifying the variety of life on Earth.<bt> 2. Genetic mutation: Genetic varieties can emerge from quality variations or from an ordinary interaction where genetic material is reworked as a cell is preparing to separate. Genetic varieties that change quality action or protein capacity can present various attributes in an organism. Sometimes the populace turns out to be distinctive to the point that it is viewed as another species. 3. Genetic drift: Genetic drift is the adjustment in the recurrence of a current quality variation in a populace because of irregular inspecting of organic entities. Genetic drift can encourage determination, by permitting the aggregation of non-versatile mutations that can encourage populace development.
Covalent bond formation requires the mutual sharing of electrons between the bonding atoms. As per the given table, the element 'E' is identified as silicon because it is located in group 14 and 3rd period. Among the given list of elements as silicon needs only four more electrons to attain octet, it has the ability to form a covalent bond.
In periodic table, elements that are classified as non-metals are located in 13th, 14th, 15th and 16th group. As per this, we have three non-metals namely I, E and B. From their position in the given table, they are identified as Boron, Silicon and Oxygen. If the number of valence electrons is less than 4, then the same is considered as the valency. On the other hand, if the number of valence electrons is greater than or equal to 4, to find the valency of the atom, the number of valence electrons must be subtracted from 8. The atomic number of boron is 5. Its electronic configuration is 2,3. As 3<4 its valency is 3. The atomic number of Silicon is 14. Its electronic configuration is 2,8,4. Hence its valency is 4. The atomic number of Oxygen is 8. Its electronic configuration is 2,6. As 6>4, 8 – 6 = 2. Hence, its valency is 2. The element 'B' which is identified as Oxygen is a non-metal with valency 2.
In the periodic table, elements that are classified as metals are located in all groups. The general concept is that those element that are present in group 2 will have 2 as its valency. As per this criteria, in the given table, element 'D' is located in group 2. As per its position, this element is identified as magnesium and it is a metal. So, Element 'D' that is identified as Magnesium is a metal with valency 2.
The trend of atomic size in the periodic table increases from period 1 to 7. According to this statement, the position of 'H' is in period 1, 'C' is in period 2 and 'F' is in period 3. The atomic size of 'F' is very large when compared to 'C' and 'H'. So, Out of H, C and F, 'F' has largest atomic size.
Atomic size and its unit of measurement: The atom has two parts namely nucleus at its center and orbits surrounding the nucleus. The space or the distance between the nucleus of the atom and the outer most shell of the atom is considered as the atomic size of the atom. This may be less for some atoms whereas very large of others. Angstroms is the measurement unit of atomic size. Atomic radius in a group: There are 18 groups in a periodic table. As we move from top to bottom in a group, we may find the atomic number of the elements increases. The atomic number gives us information about the number of electrons present in it. As the number of electrons increases, the number of orbits also increases, due to which the atomic radius also gets increased. Atomic radius in a period: There are 7 periods in the periodic table. As we move from left to right in a period, the proton quantity increases. Due to this a strong force of attraction between the electron and proton increases which in turn leads to the formation of a high nuclear charge binding them strongly and pulling them towards the nucleus. Due to this fact, the size of the element decreases as we are in a period from left to right.
There is a faster rate of breathing in the aquatic organisms. Terrestrial organisms respire through the lungs and get a sufficient amount of oxygen for breathing. The aquatic organisms get only dissolved oxygen in the water which is only in a lower amount compared to the amount of oxygen available for the terrestrial organisms. Therefore, to satisfy the needs of the body for proper functioning the aquatic organisms have to breathe faster. This is the reason for the aquatic organisms breathe faster than the terrestrial organisms.
The excretory system is responsible for the removal of metabolic wastes , regulates the chemical composition of body fluids, retains proper amount of water, salt and nutrients. Excretory organs in human body are as follows:- 1. Large intestine 2. Lungs 3. Liver 4. Kidneys 5. Skin
