Answer:
B. an element
Explanation:
An atom is smallest indivisible particle that takes part in a chemical reaction. Different atoms due to the number of their protons called atomic number gives an element. Every element is a singular atom on it's own. Combination of atoms leads to the formation of molecules and compounds.
When compounds mix together without an actual chemical change, a mixture forms.
Elements are distinct substances that cannot be split up into simpler substances. They are usually made up of only one kind of atom.
Fermentation occur in yeast is alcoholic.
Oxygen plays a critical role in respiration, the energy-producing chemistry that drives the metabolisms of most living things. We humans, along with many other creatures, need oxygen in the air we breathe to stay alive. Oxygen is generated during photosynthesis by plants and many types of microbes.
The six electrons in the outermost shell allow selenium to have a variety of valence numbers.
The valence of selenium depends on which compound it is in. Selenium is very similar to sulfur. It may have a valence of 6.
EXAMPLE:
selenium hexafluoride SeF6, selenium trioxide SeO3
May have 4;
example
selenium tetrafluoride SeF4, selenium dioxide SeO2
MAy have 2;
example
selenium difluoride SeF2, selenium dichloride SeCl2
and may have -2;
example
hydrogen selenide H2Se
