Monatomic is one atom.
Diatomic is two atoms.
d. diatomic
The symbol for carbon is simply C
Answer: The correct formula is 
Explanation:
For formation of a neutral ionic compound, the charges on cation and anion must be balanced. The cation is formed by loss of electrons by metals and anions are formed by gain of electrons by non metals.
Here magnesium is having an oxidation state of +2 called as
cation and bromine
is an anion with oxidation state of -1. Thus they combine and their oxidation states are exchanged and written in simplest whole number ratios to give neutral
.
The cations and anions being oppositely charged attract each other through strong coloumbic forces and form an ionic bond.
Answer:

Explanation:
The given reactions are:
PbCl2(aq)⇌Pb2+(aq)+2Cl−(aq) 
AgCl(aq)⇌Ag+(aq)+Cl−(aq) 
Required reaction is:
PbCl2(aq)+2Ag+(aq)⇌2AgCl(aq)+Pb2+(aq)

Helium gas: He
Hydrogen gas: H₂
Oxygen gas: O₂
Explanation:
Gases can exist at room temperature in monoatomic form or sometimes as polyatomic molecules.
A wide range of elements exists as gases at room temperature. Most of their molecules have covalent bonds between their atoms which ensures that they are stable.
Other examples are:
- Argon gas Ar
- Neon gas Ne
- Bromine gas Br₂
- Nitrogen gas N₂
Learn more:
Noble gas brainly.com/question/10874792
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