Answer:
1) B
2) A
3) A
4) D
Explanation:
An atom is neutral because it contains an equal number of protons and electrons. Though the atom actually contains neutrons, this reason does not explain the electrical neutrality of the atom.
The L shell actually contains eight electrons because the maximum number of electrons accommodated in each shell is given by 2n^2 where n is the principal quantum number. Since the L-shell corresponds to n=2 then the reason is the correct explanation of the assertion.
The valency of atoms is determined by the number of electrons in the outermost shell of the atom. Remember that atoms having a filed valence shell(eight electrons in the outermost shell) have a valency of zero. Hence the noble gases possess a zero valency. Thus the reason is the correct explanation of the assertion.
Nitrogen forms its ion by electron gain and not by electron loss because nitrogen forms an anion. This anion is formed by a gain of three electrons. The assertion is false but the reason is true.
Answer:
B. He was the first to observe live cells in a sample of pond water.
Explanation:
He was a self taught man that created the first microscopes which allowed him and others to see tiny organisms.
The other answers are not correct as Hans made the first microscope, cells existing in liquids were not a critical part of micro biology, and it was Schlieden and Schwann who created the cell theory that stated that all living things were made of cells.
What did you include in your response?
- For a cell to survive, ion concentrations inside and outside the cell need to be the same.
- If extra ions are not pumped out of the cell, water can enter the cell, causing it to swell and burst.
Organisms that live in water are not totally independent of soil as a resource. These organisms depend on aquatic plants for food and other substances. These aquatic plants in turn require minerals for their sustenance. These minerals are carried to waterbodies from soil by rivers, rainwater etc.
