Carbon dioxide has a double bond between the carbon and oxygen molecules. Since there is a moderately large electronegativitiy difference between C and O, the bond can be described as polar covalent.

Though the bonds themselves are polar, the overall symmetry of the molecule means that carbon dioxide has a net zero dipole and is a nonpolar compound.

In a covalent bond, electrons are shared between two nonmetals. If there is a metal in the compound, that is called an ionic compound, not a covalent compound. Ionic bonds involve the complete transfer of an electron from one species to another.

An ionic bond is a bond between a metal (Rb) and a nonmetal(Cl)

Ionic compounds are formed between metals, which want to loose electrons, and nonmetals, which want to gain electrons. The sodium (Na) will completely transfer an electron to the chlorine (Cl), giving both atoms a complete octet without sharing electrons.

Covalent compounds generally form between two nonmetals that will both share electrons to complete their octets. Metallic compounds are built from only metals. Polyatomic ions will have a formal charge.

Covalent bonds are formed when two nonmetals are bonded together. This covalent bond means that the electrons are shared by the two atoms in order to satisfy each atom's octet. There is very little difference in the electronegativities of the two atoms involved in the bond, so neither atom pulls the electrons closer to its nucleus.

Ionic bonds are formed between a metal and a nonmetal. Due to the dramatic difference between the electronegativities of metals and nonmetals, the electrons are pulled tightly to the nonmetal, and away from the metal nucleus. This results in each atom having a full octet, even though the electrons are not shared.

Carbon and oxygen are both nonmetals, so we would expect only covalent bonds in carbon dioxide.

Atoms share electrons in covalent bonds, not ionic. In ionic bonding, one or more electrons from an atom with a lower ionization energy are transferred to an atom with greater electron affinity. 

The definition of ionic compounds are three-dimensional arrays of atoms held together by strong ionic bonds. Ions are charged particles that have either gained or lost a certain number of electrons. They have great crystalline strength because of the strong electrostatic forces between the ions.

H bonding is when a H is bonded to either N, O, or F. In the third molecule, the O is only double-bonded to the C; it is not bonded to a single H. All other choices have a N, O, or F bonded to a H

Electronegative atoms disproportionately pull covalently bonded electrons toward themselves, which leaves hydrogen with partial positive character. 

For hydrogen bonding to occur there must be a molecule with a hydrogen bonded to either F,O,N. This is present in water and methanol which both have O-H bonds. There can be hydrogen bonding between two water molecules, and there can be hydrogen bonding between two methanol molecules. The key to this problem is recognizing that it is asking for a situation in which hydrogen bonding is occuring between two separate molecules.  

Hydrogen bonding is the association of a hydrogen and one of the three most electronegative elements F,O,N of neighboring molecules. The hydrogen, because it is bonded to one of these elements, aquires a partially positive charge, F,O, or N develops a partially negative charge. The partially positive hydrogen will associate, not bond, with the F,O, or N of a seperate molecule. Remeber that hydrogen bonding is an intermolecular property, so it is occuring between separate molecules.