The percentages of carbon and hydrogen 84.37% and 15.693% respectively.
<h3>What is a molar mass ?</h3>
The mass of a certain chemical element or chemical compound (g) divided by the amount of material is known as the molar mass (mol). By multiplying the standard atomic masses (in g/mol) of the component atoms, one may get the molar mass of a compound.
Molar mass of the compound is the mass of 1 mole of compound which is the sum of masses of each element.

Mass of 1 mole of compound= mass of carbon + mass of hydrogen+ = 9(12) + 20(1)= 128 g.
Percentage by mass of carbon =
%
= 108/128 * 100
= 84.37 %
Percentage by mass of carbon =
%
=20/128 *100 =15.63 %
The percentages of carbon and hydrogen 84.37% and 15.693% respectively.
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The mass of the reactants and the mass of the products are no equal.
<u>Answer: </u>The correct answer is Option D.
<u>Explanation:</u>
Unstable isotopes are defined as the isotopes which have excess of neutrons as compared to the stable form of the nucleus of an atom.
These isotopes attain stability by undergoing a spontaneous nuclear decay. The isotopes which are unstable have another name and are known as radioactive isotopes or radioisotopes.
These isotopes undergoes decay by 4 processes: Alpha decay, beta decay, gamma emission and positron decay.
Hence, the correct answer is option D.
2Ag+(aq) + CO2-_3(aq)-----------Ag2CO3