Answer : The oxidizing element is N and reducing element is O.
is act as an oxidizing agent as well as reducing agent.
Explanation :
An Oxidizing agent is the agent which has ability to oxidize other or a higher in oxidation number.
Reducing agent is the agent which has ability to reduce other or lower in oxidation number.
The given reaction is :

act as an oxidizing agent.
The oxidation number of N in
is calculated as:
(+1)+(x)+3(-2) = 0
x = +5
And the oxidation number of N in
is calculated as:
(+1)+(x)+2(-2) = 0
x = +3
From the oxidation number method, we conclude that the oxidation number reduced this means
itself get reduced to
and it can act as an oxidizing agent.
act as a reducing agent.

The oxidation number of O in
is calculated as:
(+1)+(+5)+3(x) = 0
x = -2
The oxidation number of O in
is Zero (o).
Now, we conclude that the oxidation number increases this means
itself get oxidized to
and it can act as reducing agent.
Answer: A substitution is a mutation that exchanges one base for another (i.e., a change in a single "chemical letter" such as switching an A to a G). Such a substitution could: change a codon to one that encodes a different amino acid and cause a small change in the protein produced.
Explanation: I know this is correct just trust me and please mark me as brainiest.
The formula of the ppt. formed is PbSo4 , which is inslouble.