A is the answer I know bc I take biology
The answer is b because that’s it
<h3>Answer
</h3>
Option C= ions are exchanged between two compounds.
<h3>Explanation
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A double displacement reaction, also known as a double replacement reaction or metathesis, is a type of chemical reaction where two compounds react, and the positive ions (cation) and the negative ions (anion) of the two reactants switch places, forming two new compounds or products. For example,
Na2S + 2HCl → H2S + 2NaCl
Option D is incorrect because electrons are exchanged between the atoms in oxidation –reduction reactions.
Polarity is classified by the difference in two or more atoms that is the electronegativity value (EN)
En for Fluorine =4.0, Bromine=2.96 Chlorine =3.16 Hydrogen=2.1
for the molecules
HF=4.0-2.I=1.9
HCl=3.16-2.1=1.06
Hbr=2.96-2.1=0.86
Hi=2.66-2.1=0.56
H2=2.1-2.1=0
from the EN value above HF has the mast highest value of EN hence it is the most polar.
Answer: it’s number 2 add a catalyst
Hopefully this helped :)