Answer:
<u><em>Pentane </em></u>
Explanation:
since we have in here CH3-CH2-CH2-CH2-CH3 5 Carbon atoms and 12 Hydrogen making it 
Kindly checkout the attached pic. It contains all your required questions.
Put the <em>wood and excess oxygen in a closed contai</em>ner that contains some device that can create a spark (to start the reaction).
Determine the <em>mass of container + contents</em>.
<em>Start the reaction</em> and, after everything has cooled down, again determine the <em>mass of container + contents</em>.
If the two masses are the same, you have demonstrated that the reaction obeys the Law of Conservation of Mass.