Elements [or radicals] with valency one are monovalent, those with valency two are divalent, and those with valency three are trivalent.
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What is the Valency of an Element / Radical?
Valency Divalent [2]
Element / Radical Oxide [Oxygen]
Symbol O
Ion O2-
Explanation:
Vaccination is the administration of a vaccine to help the immune system develop protection from a disease. Vaccines contain a microorganism or virus in a weakened, live or killed state, or proteins or toxins from the organism. In stimulating the body's adaptive immunity, they help prevent sickness from an infectious disease. When a sufficiently large percentage of a population has been vaccinated, herd immunity results. Herd immunity protects those who may be immunocompromised and cannot get a vaccine because even a weakened version would harm them.[1] The effectiveness of vaccination has been widely studied and verified.[2][3][4] Vaccination is the most effective method of preventing infectious diseases;[5][6][7][8] widespread immunity due to vaccination is largely responsible for the worldwide eradication of smallpox and the elimination of diseases such as polio and tetanus from much of the world.
Answer:
A) Atoms share one or more pairs of electrons.
Explanation:
Covalent bonding occurs when pairs of electrons are shared by atoms. Atoms will covalently bond with other atoms in order to gain more stability.
English please i don’t understand thank you very much
Answer:
ecosystem
Explanation:
The level of organization shown in the example is "ecosystem" because the example represnts interaction between two different population with acorns on the land.
Ecosystem is defined as the interaction of groups of organisms in biological domain with abiotic enviornment.
The example, groups of organisms include "squirrels and birds" and abiotic enviornment include "acorns" or "nuts".
Hence, the correct option is "ecosystem".