The reaction for burning of charcoal or complete combustion is as follows:

From the above balanced reaction, 1 mole of carbon releases 1 mole of
gas.
Converting mass of charcoal into moles as follows:

Molar mass of pure carbon is 12 g/mol thus,

The same moles of
is released. Converting these moles into mass as follows:
m=n×M
Molar mass of
is 44 g/mol thus,

Converting mass into kg,

Thus, total mass of gas released is 5.5 kg.
The correct answer is a. This is because the pH of a solution is defined as -log10(concentration of H+ ions). An inverse logarithmic scale such as this means that a solution with a lower concentration of H+ ions will have a higher pH than one with a higher concentration. Therefore we know that the pH of the second sample will be higher than the first.
Since the logarithmic scale has the base 10, a change by 1 on the scale is a consequence of multiplication/division of the H+ concentration by a factor of 10. As the scale is inverse, this means that a decrease of concentration by factor 1000 is equivalent to increasing the pH by (1000/10) = 3.
NaHCO3 is the right answer
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