Once the torch is lit, the acetylene flow must be increased until the flame stops smoking <span>before the oxygen is turned on for adjustment in order to keep the tip of the torch cool.
You should also note that while lighting the torch, you should keep the spark lighter near the tip but not covering it.</span>
Answer: The result is presented in proportion which gives a clearer understanding and accurate result.
Explanation: Percentage change in mass is the proportion of the initial mass of a substance changed after sometime. The results is presented as a percentage making it more accurate and can help to give future reference to weight calculations.
Change is Mass is the mass of a substance left after sometime mostly given in grams. It is not as accurate as percentage change in mass. It is generally better to show results in percentage change in mass as it gives a better understanding of what mass of a substance was lost after a given period or after application of energy like Heat or increased temperature.