<u>Answer:</u> The unbalanced chemical equation is written below.
<u>Explanation:</u>
Unbalanced chemical equation does not follow law of conservation of mass.
In an unbalanced chemical equation, total number of individual atoms on the reactant side will not be equal to the total number of individual atoms on the product side.
The chemical equation for the reaction of diboron trioxide and magnesium metal follows:

Hence, the unbalanced chemical equation is written above.
Answer:
592 K or 319° C
Explanation:
From the statement of Charles law we know that the volume of a given mass of gas is directly proportional to its absolute temperature at constant pressure. Thus;
V1/T1= V2/T2
Initial volume V1 = 1.75 L
Initial temperature T1= 23.0 +273 = 296 K
Final volume V2= 3.50 L
Final temperature T2 = the unknown
T2= V2T1/V1= 3.50 × 296 / 1.75
T2 = 592 K or 319° C