Reaction 3 is the double displacement reaction.
Double displacement reaction occurs when the negatively and the positively charged ions of the compounds interchange their position when the new compound in the product is formed.
<h3>Which is a double displacement reaction?</h3>
In the <u>first reaction</u>, the element lead (Pb) is not an ion and no exchange of the cations or the anions occurs hence it is not a double displacement reaction.
In the <u>second reaction</u>, one compound is getting split into two new compounds and is a decomposition reaction.
In the <u>third reaction</u>,
in
and
in
are anions and cations and exchanges their places to produce two new compounds 
In the <u>fourth reaction</u>, a single compound is generated as the result of the combination reaction and hence, it is not the double displacement reaction.
Therefore,
is the double displacement reaction.
Learn more about double displacement reaction here:
brainly.com/question/10091171
A) number of neutrons in the nucleus... all isotopes of an element contain the same number of protons which is equal to that elements atomic number...
hope this helps!
Answer:
0.05263158 atm
Explanation: mmHg to Atmosphere Conversion Example. Task: Convert 975 mmHg to atmospheres (show work) Formula: mmHg ÷ 760 = atm Calculations: 975 mmHg ÷ 760 = 1.28289474 atm Result: 975 mmHg is equal to 1.28289474 atm. This is an example for how i got the answer.