This is called a combustion reaction. A combustion reaction involves oxygen gas. Most combustion reaction are exothermic as they give off heat. When organic molecules (containing carbon and hydrogen) combust the reaction products are carbon dioxide and water as well as heat or light. Combustion reactions may be complete or incomplete, a complete combustion releases more energy than incomplete combustion.
It is important to use the same balance throughout the entire experiment since the calibration of each balance is not the same and changing balances could result in a systematic error.
There are three types of errors that could affect the results of the experiment. The effect of random or indeterminate errors is hard to predict, its effect on the results of the experiment could be different every time. The second type of error is the systematic or determinate error, which causes a shift in results in a specific direction. The last type of error in an experiment is human error.
The type of error that could be related to the use of different balances throughout the experiment is the systematic error. Instruments could be a source of error especially if they are poorly calibrated. Also, analytical balances are calibrated differently which may result in inaccuracy in the weighing of chemicals.
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Answer: 1.67 kg
Explanation:
The quantity of heat required to raise the temperature of a substance by one degree Celsius is called the specific heat capacity.

Q = Heat absorbed=
=
(1kJ=1000J)
m= mass of substance = ?
c = specific heat capacity = 
Change in temperature ,
Putting in the values, we get:

(1kg=1000g)
Thus the mass (in kg) of the copper sample is 1.67
Answer:
A
Explanation:
The answer A is the best answer because it contains the most general characteristic of a chemical change.