Friction is not useful in Machinery sometimes, Since it leads to the wear and tear of machine parts.
Halogens
Explanation:
Halogens are a group of non-metals located in the seventh group on the periodic table. The will only gain one electron during a chemical reaction.
- Halogens have a seven electrons in their outermost shell.
- To complete the number of electrons in this shell, they need to gain an additional electron.
- One more electron makes the halogen similar to the corresponding noble gas which is very stable.
- Halogens are very reactive groups of elements and are highly electronegative.
- They have a high affinity for electrons.
- These elements are fluorine, chlorine, bromine, iodine and Astatine.
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Answer:
(2) Organelles must work together and their
activities must be coordinated
Explanation:
Organelles are usually located in cells. They are saddled with the role of performing specific functions in the cells for the overall functioning of life. In eukaryotic cells, the organelles are membrane bounded but in prokaryotic or primitive cells such is not the case.
Examples of cell organelles are ribosome, food vacuole, nucleus e.t.c. Just like organs in the body, organelles must work together in order to enhance life.
The periodic table of elements arranges all of the known chemical elements in an informative array. Elements are arranged from left to right and top to bottom in order of increasing atomic number. Order generally coincides with increasing atomic mass. The rows are called periods.
