Answer:
4477381.7 calories/pound
Explanation:
It is given that,
When a candle burns it produced 41,300 Joules per 1 gram.
We need to convert it into calories per pound.
We know that,
1 cal = 4.184 J
⇒ 1 J = (1/4.184) cal
1 pound = 453.592 grams
⇒1 g = (1/453.592) pounds
Now,

Hence, 41,300 Joules/gram = 4477381.7 calories/pound.
I am not sure about the first question but the temperature has an important role in this situation because as the temp goes up particles moves at a faster speed and spread out every where.
Answer:
Mass = 0.158 g
Explanation:
Formula used,
P V = n R T
Or,
n = P V / R T
Putting values,
n = 0.948 atm . 0.025 L / 0.0821 L.atm.K⁻¹.mol⁻¹ . 291.45
n = 0.00099 mol
Note: we have changed pressure from mmHg to atm, volume from mL to L and temperature from C to K)
Also,
Mass = n . Molecular Mass
Mass = 0.00099 mol × 159.808 g/mol
Mass = 0.158 g
When magnesium is burned, it reacts with oxygen in air not with the fire. The fire is the energy needed for the reaction to happen. Magnesium reacts with oxygen forming magnesium oxide. The light emitted from the reaction is because the reaction produced a lot of heat.
Recorded by a seismograph.