Answer:
The mass number (symbol A, from the German word Atomgewicht [atomic weight]),[1] also called atomic mass number or nucleon number, is the total number of protons and neutrons (together known as nucleons) in an atomic nucleus. It is approximately equal to the atomic (also known as isotopic) mass of the atom expressed in atomic mass units. Since protons and neutrons are both baryons, the mass number A is identical with the baryon number B as of the nucleus as of the whole atom or ion. The mass number is different for each different isotope of a chemical element. Hence, the difference between the mass number and the atomic number Z gives the number of neutrons (N) in a given nucleus: N = A − Z.[2]
The mass number is written either after the element name or as a superscript to the left of an element's symbol. For example, the most common isotope of carbon is carbon-12, or 12
C
, which has 6 protons and 6 neutrons. The full isotope symbol would also have the atomic number (Z) as a subscript to the left of the element symbol directly below the mass number: 12
6C
.[3]
<span>Wetlands help reduce erosion through B. sediment trapping.
Soil and rocks are trapped and then there is no erosion or crumbing of the ground and rocks.
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If the cell membrane were not selectively permeable, then unwanted substances would transfer through instead of being blocked out. Think of it like this: you have a sifter with various sizes of spice in it. You only want the finer grains of spice in your food, so when you shake the sifter, the larger pieces of spice don't fit through the small holes that only allow fine grains. Then you are left with the small spices in your food and the large ones stuck in the sifter.
Hopefully this helps and I wasn't too confusing :)
<em />I believe the answer is (D).
The oceans around the globe gets heated up due to the heat of the sun. This hot water is then passed through to the colder regions of the globe by the method of convection. This is a continuous process. This warm water has helped in the survival of variety of aquatic animals and plants. I hope it helps you.