Please help me with this multiply choice science question.

In numbering carbon atoms in the parent chain of a hydrocarbon, why would you number from right to left, rather than left to right

If i initially have a gas at a pressure of 12 atm, a volume of 23 liters, and a temperature of 200 k, and then i raise the pressure to 14 atm and increase the temperature to 300 k, what is the new volume of the gas?

Astudent reacts 13 moles of iron with 21 moles of oxygen according to the following equation: