Answer: A
Explanation:
A contour interval is a vertical distance or difference in elevation between contour lines. Index contours are bold or thicker lines that appear at every fifth contour line.
Answer :
During diffusion, when the concentration of the molecules on both sides of the membrane is the same, the molecules will continue to move across the membrane in both the direction.
Answer 3 : It allows single-celled organism to reproduce, and other organism to repair damage tissues and grow.
Answer 4: The nucleus is an organelle that is surrounded by the cytoplasm, a jelly-like fluid.
Explanation :
Diffusion : It is a process where liquid moves from higher concentration to the lower concentration through permeable membrane.
When the concentration of the molecules on both sides of the membrane is same and the membrane is permeable membrane then diffusion will occur and the molecules will moves continuously across the membrane in both the direction.
Answer 3 :
Mitosis : It is a process of cell division. In this process, nucleus divides into two daughter cell and each daughter cell contains same number of chromosomes as present in parent nucleus.
The main purpose of the mitosis is to repair damaged tissues and growth.
Answer 4 :
Nucleus is a type of cell organelle. It is present in both animal and plant cells and it is the brain of the cell. It is present only in eukaryotic cell.
Nucleus is an organelle which is surrounded by the cell membrane which protects its from the other cells.
Cytoplasm is a jelly-like fluid which is present in the cell membrane which is made up of salt and water.
1. The reactivity among the alkali metals increases as you go down the group due to the decrease in the effective nuclear charge from the increased shielding by the greater number of electrons. The greater the atomic number, the weaker the hold on the valence electron the nucleus has, and the more easily the element can lose the electron. Conversely, the lower the atomic number, the greater pull the nucleus has on the valence electron, and the less readily would the element be able to lose the electron (relatively speaking). Thus, in the first set comprising group I elements, sodium (Na) would be the least likely to lose its valence electron (and, for that matter, its core electrons).
2. The elements in this set are the group II alkaline earth metals, and they follow the same trend as the alkali metals. Of the elements here, beryllium (Be) would have the highest effective nuclear charge, and so it would be the least likely to lose its valence electrons. In fact, beryllium has a tendency not to lose (or gain) electrons, i.e., ionize, at all; it is unique among its congeners in that it tends to form covalent bonds.
3. While the alkali and alkaline earth metals would lose electrons to attain a noble gas configuration, the group VIIA halogens, as we have here, would need to gain a valence electron for an full octet. The trends in the group I and II elements are turned on their head for the halogens: The smaller the atomic number, the less shielding, and so the greater the pull by the nucleus to gain a valence electron. And as the atomic number increases (such as when you go down the group), the more shielding there is, the weaker the effective nuclear charge, and the lesser the tendency to gain a valence electron. Bromine (Br) has the largest atomic number among the halogens in this set, so an electron would feel the smallest pull from a bromine atom; bromine would thus be the least likely here to gain a valence electron.
4. The pattern for the elements in this set (the group VI chalcogens) generally follows that of the halogens. The greater the atomic number, the weaker the pull of the nucleus, and so the lesser the tendency to gain electrons. Tellurium (Te) has the highest atomic number among the elements in the set, and so it would be the least likely to gain electrons.
