We need to keep in mind that the compound is neutral.
H2SO3
2(+1)+S+3(-2)=0 (since its neutral)
2+S-6=0
S-4=0
S=4
Therefore the oxidation number for sulfur is +4.
Answer:

Explanation:
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In this case, since the equation for the ideal gas is:

For each gas, given the total volume, temperature (28.1+273.15=301.25K) and moles, we can easily compute the partial pressure as shown below:

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19. The atomic number is the same as protons and electrons unless it have a - or a + charge the electrons are going to change