(3) N is the correct answer.

Electronegativity indicates how strongly an atom of an element attracts electrons in a covalent bond. See table S.  Also, by memorizing the electronegativity trend of the periodic table, we can see that electronegativity increases from bottom to top in a column and from left to right across a group.

(2)    Is the correct answer.

The definition of a covalent bond is electrons that are shared between 2 atoms.  Hydrogen and Sulfur share electrons to form a covalent bond.  This compound is similar to Water, where 2 hydrogens share electrons with one oxygen.

(1)    Is the correct answer.

Carbon atoms are tetravalent, or capable of bonding with four other atoms at the same time.  Carbon forms the basis of organic chemistry, able to bond in chains, rings, and networks.

(2) is the correct answer.
Barium binds with 2 chlorine atoms to form BaCl2, which is also known as Barium Chloride.  It’s structure looks like this:

Each Chlorine carries 7 electrons and the Barium carries 2 electrons in its outer shell.When the Barium binds with 2 Chlorines, the 8 valence electrons are filled on each Chlorine. This is an ionic bond.

(3) is the correct answer: Sodium nitrate

Sodium (Na) is a metal and readily donates a single electron (a primary property of a metal) to form Na(+1). The bonds between the nitrogen and the oxygens are approximately covalent. The bonding between the Na(+1) and the (NO3(-1)) is essentially an ionic bond.

NaHCO3 is the chemical formula for baking soda.

This is the structure for ethanoic acid.

You can calculate the mass by knowing that mass = volume x density.

The density of carbon dioxide is 1.8g/L.

.2L x 1.8(g/L) = 3.6 grams of CO2 gas replaced the air in the beaker.