Here are some trends you should know.
Electronegativity increases as you go right and up along the periodic table.
So, (1) is wrong
Atomic mass increases as you go right and down along the periodic table.
So, (2) is wrong
Proton number or atomic number increases as you go right and down in the table.
So, (3) is correct
Metallic character increases as you go left and down along the periodic table.
So, (4) is wrong
Answer:
- <u><em>Option D. There will be a shift toward the reactants.</em></u>
Explanation:
The reaction is:

The application of LeChatelier's principle leads to consider the <em>heat</em> as a <em>reactant</em> or a product depending on if it is on the left side or the right side.
In this reaction, the <em>heat</em> is on the left side, thus it must be considered a <em>reactant</em>.
Decreasing the temperature is equivalent to remove or consume heat. Thus, the reaction must shif to the left to compensate that reduction of heat. That is the reverse reaction shall be favored.
In conclusion, <em>there will be a shift toward the reactants.</em>
A sample of oxygen gas had a volume of 2.50 L at STP.