A secondary amine is an amine (nitrogen atom) that is attached to two carbon-containing groups (alkyl groups or aryl groups). The nitrogen in ephedrine is attached to two alkyl groups, making it a secondary amine.

Primary amines are generally written as . Secondary amines are generally written as . A tertiary amine will be bound to three different R-groups. Quaternary amines require a positive charge on the nitrogen atom to accommodate a fourth R-group.

An amino group is a nitrogen-containing functional group, and is the part pictured on the right of the given molecule. This amine has three substituents: the alkyl ketone, the methyl, and the ethyl. Hydrogens do not count as "substituents." Any amine with three substituents is considered a "tertiary" amine.

This amine is chiral because it has four different substitutions at the nitrogen atom, which is the definition of chirality. 

Note: "tetriary" is not a real term in organic chemistry.

A tertiary amine has three organic groups bonded to it. Triethylamine has three ethyl groups bonded to it, so that is the correct answer. Ammonia is _, so it has no organic groups attached. Piperidine is a six-membered ring with a nitrogen as one of the members, making it a secondary amine. Aniline is a benzene ring with a  bonded to it, so it is a primary amine.

C is the correct answer.

The molecule pictured above is an anime because it contains a nitrogen group bonded to two hydrogen atoms and one R-group. A shows an aldehyde, B shows an amide, and D shows a carboxylic acid.

For this question, we're being asked to identify a characteristic of ammonia.

First, we need to remember what ammonia is. Ammonia is a molecule that consists of a nitrogen atom bonded to three separate hydrogen atoms. In doing so, these three bonds contribute to six of the valence shell electrons for nitrogen. The remaining two valence electrons exists on the nitrogen atom as a lone pair. Thus, there is only one lone pair of electrons (pair being two).

Also, the lone pair of electrons on ammonia allows it to act as a Lewis base by donating them (not a Lewis acid, which accepts electrons). Furthermore, this tendency for ammonia to donate its electrons would make it a nucleophile, not an electrophile.

In this question, we're shown the structure of the nucleoside called guanosine. We're asked to determine how many amide functional groups exist in this molecule.

First, to answer this question, we need to know what an amide functional group is. Amides consist of a carbon atom double bonded to an oxygen atom, and single bonded to a nitrogen atom. Note that this is distinct from the similarly named amine functional group, which contains a nitrogen atom with a lone pair of electrons and single bonded to three other atoms, which can be hydrogen or "R-groups" containing carbon atoms.

When looking at the molecular structure of guanosine, we can see that there is only a single amide group.

The molecule's longest carbon chain has 3 carbons (thus, "prop"), and the lack of double bonds makes it an alkANe (thus "propan-"). The only functional group on this molecule is the amino group (thus "propanamine"), located on carbon number 1 if read from right to left, or carbon number 3 if read from left to right. The IUPAC rules state that the correct name for a molecule numbers the carbon chain such that functional groups get the lowest numbers possible. Thus "1-propanamine."