The atomic mass on the periodic table represents the sum of number of protons and number of neutrons.
Atomic mass = Number of protons + number of neutrons
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A free-radical substitution reaction is likely to be responsible for the observations. The reaction mechanism of a reaction like this can be grouped into three phases:
- Initiation; the "light" on the mixture deliver sufficient amount of energy such that the halogen molecules undergo homologous fission. It typically takes ultraviolet radiation to initiate fissions of the bonds.
- Propagation; free radicals react with molecules to produce new free radicals and molecules.
- Termination; two free radicals combine and form covalent bonds to produce stable molecules. Note that it is possible for two carbon-containing free-radicals to combine, leading to the production of trace amounts of long carbon chains in the product.
Initiation

where the big black dot indicates unpaired electrons attached to the atom.
Propagation






Termination

CH4 is an emprirical formula as it shows the simplest ratio of the numbers of different atoms present in the molecule. The empirical formula for CH4 is also the same as the molecular formula.
The other compunds can be simplified so they are not the empirical formula of compounds.
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Answer:
Just use a text book.. So that you get the concept
Answer:
B. Electrons are gained, so the oxidation number decreases.
Explanation:
Reduction is the <em>gain of electrons</em>.
Oxidation number is the charge that an atom <em>appears</em> to have when we count its electrons in a specific way.
Electrons have a negative charge so, if an atom gains electrons, its charge (oxidation number) becomes more negative. The oxidation number decreases.
If electrons are given off, the atom is being oxidized. Loss of electrons is <em>oxidation</em>.