Answer:
QR and SV
RS and TU
Step-by-step explanation:
The first reaction represented is a decomposition reaction due to the fact the bonded pair are being split apart.
The second equation is a single displacement because the B and C have switched places, which is the only change making it a single displacement. If there had been another bond and A had also moved, it would be double.
V = a²h/3
Plugging values in we get 8.67X10^7, or 86,700,000