im not sure but i know its either phosphoric acids, acetic acids, carbon monoxide, or weak acids i hope this helps :)
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He said that compounds are formed when atoms of different elements combine
A mixture.
All the compounds existing in the universe are formed.
No, compounds are formed.
Compounds
Compounds are pure substances formed when two or more different elements combine.
if two or more atoms combine, it chemically forms something yes.
Nitrogen oxide can refer to a binary compound of oxygen and nitrogen, or a mixture of such compounds.
When elements combine chemically compounds are formed. For instance, when hydrogen and oxygen gases chemically combine, water is formed. Note that if a molecule is made up of only one element, it is referred to as an element, not a compound.
Charged atoms, called ions, form ionic compounds when they combine chemically with one another.
Electronegativity can help, but experience and factual knowledge of each case is needed for most compounds.