A Lewis base is a compound that donates a pair of electrons. The only compound shown that possesses an electron pair that can be donated is ammonia. is the Lewis base. and are Lewis acids and are therefore wrong. Neither carbon dioxide nor methane are Lewis bases.

The correct ranking from most basic to least basic is:

The best bases are negatively charged, and the worst bases are positively charged (acidic). The stronger the base, the weaker (more stable) it's conjugate acid. An alkane is a very stable conjugate acid, which tells us that is the most basic of the set.

We know based on charge alone, that is more basic than but less basic than or .

We know that is more basic because the electronegativity of is less than that of . This means the lone pair of electrons on are held less tightly and more likely to pick up a proton.

The molecule's longest carbon chain has 6 carbons (thus, "hex-"), and the lack of double bonds makes it an alkane (thus "hexane"). The longest chain is a ring structure (thus "cyclohexane"), and the one branching group is a carbon chain consisting of one carbon and no double bonds (a "methyl" group). Because there are no other functional groups on the molecule there is no need to put a number before the location of the methyl group (thus "methylcyclohexane").

1. Benzene

2. Imine

3. Aldehyde

The correct ranking from most basic to least basic is:

The best bases are negatively charged, and the worst bases are positively charged (acidic). The stronger the base, the weaker (more stable) it's conjugate acid. An alkane is a very stable conjugate acid, which tells us that is the most basic of the set.

We know based on charge alone, that is more basic than but less basic than or .

We know that is more basic because the electronegativity of is less than that of . This means the lone pair of electrons on are held less tightly and more likely to pick up a proton.

The reaction shown is a Markovnikov addition of a hydracid (HX) across a double bond. According to Markovnikov's rule, the hydrogen gets added to the lesser-substituted carbon in the double bond, and the halide (in this case, ) gets added to the more-substituted carbon. Thus, the correct answer is .

An elimination reaction occurs when there is a release of atoms in a given compound to produce two or more products. In the reaction given a hydrogen and chloride atom are eliminated from the original compound to form hydrochloric acid and ethylene.

Cyanide is a weak base and a good nucleophile, and the solvent is aprotic; therefore, the product is favored. This involves 100% inversion of stereochemistry; therefore II is favored.

E1 reactions occur in two steps. First, the leaving group is removed, yielding a carbocation. Second, a weak base removes a proton from the carbon adjacent to the carbocation carbon. Thus, to favor E1, a protic solvent is desired in order to stabilize the carbocation. Weak bases favor an E1 mechanism.

A Lewis base is a compound that donates a pair of electrons. The only compound shown that possesses an electron pair that can be donated is ammonia. is the Lewis base. and are Lewis acids and are therefore wrong. Neither carbon dioxide nor methane are Lewis bases.