Carbon is a tetravalent element, meaning it can form up 4 covalent bonds with other elements, especially other carbon atoms. This allows for the formation of many different carbon-containing elements of differing sizes, shapes, and structures.

By definition, a saturated hydrocarbon is a compound that contains no double or triple bonds-all single bonds. Of these choices, propane (-ane suffix indicates that it is an alkane, which contains only single bonds) is the only saturated hydrocarbon.

Hexane is a hydrocarbon consisting of 6 carbon atoms and 12 hydrogen atoms, making it nonpolar. Because it has no donatable hydrogen ions, it is also considered aprotic.

The inductive effect of the  group stabilized the carbocation further away from the electron withdrawing group, causing the addition of the  to occur there.

A double bond contains one sigma bond and one pi bond.

A triple bond contains 2 pi bonds and a single sigma bond. 

A Grignard reagent is equivalent to a carbanion. Electron withdrawing groups help stabilize the negative charge on the carbon while electron donating groups will destabilize it. Therefore,  is the only correct answer. 

In this question, we're asked to identify a compound that has no dipole moment.

To answer this question, we need to understand what a dipole moment is. Some compounds have an uneven distribution of charge around their molecular structure. This uneven distribution is normally due to differences in electronegativity of the various atoms that make up that molecule. This uneven distribution of electrical charge is what is known as a molecule's dipole moment. However, while electronegativity differences are important, it is also vital to take into consideration the molecular structure of the compound in question because, many times, two dipole moments can cancel each other out and lead to a net dipole moment of zero.

Now, we'll need to look at each answer choice in order to see whether there will be an uneven distribution of electrical charge.

First, let's start with water. We know that water consists of an oxygen atom singly bound to two other hydrogen atoms. Furthermore, the oxygen has two lone pairs of electrons. This causes the water molecule to take on a bent shape. Moreover, the electronegativity of oxygen is much greater than that of hydrogen. Consequently, we can expect there to be a net dipole moment in water.

Next, let's take a look at dichloromethane, . In an ordinary molecule of methane, we know that the four hydrogen atoms are situated around the central carbon atom in a tetrahedral fashion. Likewise, dichloromethane also has a tetrahedral structure. The difference, however, is that two of the hydrogens are now chlorine atoms. As a result, two of the chlorine atoms will be pointed in the opposite direction to the two hydrogen atoms. Furthermore, chlorine and carbon have a massive difference in electronegativity. As a result, we would expect dichloromethane to have a net dipole moment.

Let's turn our attention to carbon monoxide. This compound consists of a carbon atom triple bonded to an oxygen atom, with a lone pair of electrons on both atoms. Since these are the only two atoms in the compound, the structure is relatively simple as it is just linear. Moreover, there is a substantial difference in the electronegativity of carbon and oxygen and, thus, we would expect carbon monoxide to have a net dipole moment.

Finally, let's look at carbon dioxide. In this compound, we have a central carbon atom which is double bonded to two other oxygen atoms. Just as with carbon monoxide, the structure of carbon dioxide is simply linear. And once again, due to the difference in electronegativity between carbon and oxygen, there is a dipole moment between the central carbon atom and each of the oxygen atoms. However, this doesn't mean that the molecule as a whole has a dipole moment!! Remember, we also need to take the structure of the molecule into account. Because the two oxygen atoms are arranged around the carbon in a linear fashion and are pointing directly away from each other, the two dipole moments between carbon and oxygen will exactly cancel each other out. Thus, carbon dioxide will not have a net dipole moment.

In this question, we're presented with the structure of pyrrole. We're told that the compound is aromatic and is stabilized by resonance. We're then given a number of resonance structures, and we're asked to decide which is a correct one.

In order to answer this question, we'll need to consider the structure of pyrrole, and see which resonance structures we can obtain. To do this, we'll need to do some electron pushing.

Also, it's critical to recognize that the nitrogen atom in pyrrole has a lone pair of electrons. This lone pair is situated in the nitrogen's p orbitals. This allows the p orbital electrons to participate in pi bonding with the other two carbon-carbon double bonds found in the molecule. Because there is a lone pair of electrons on the nitrogen atom, we can begin our "electron pushing" starting with these electrons first.

After pushing electrons as shown above, we end up with the following possible resonance structure.

Thus, this is the correct answer. All of the other resonance structures shown are not possible. You can do electron pushing to try it out for yourself.