Which of the following statements is (or are) true?
I. All polar molecules have dipole moments.
II. All polar molecules have oppositely charged regions.
III. A polar molecule is attracted to other molecules because of electrostatic forces.
IV. All polar molecules have hydrogen bonding.
A. I and II only
B. I, II, and IV only
C. II, III, and IV only
D. I, II, and III only
I believe the answer is A or D
I, II, III
I believe I is true.
I think II is true.
III is true sometimes but not always. I would agree if it said attracted to other polar molecules. It doesn't say that so I would rule III out.
IV is not true.
The correct answer is D.
Statement I is true. All polar molecules have dipole moments because they contain polar bonds, which occur when there is an unequal sharing of electrons between atoms.
Statement II is true. All polar molecules have oppositely charged regions due to the uneven distribution of electron density.
Statement III is true. A polar molecule is attracted to other molecules because of electrostatic forces. The positive region of one polar molecule is attracted to the negative region of another polar molecule, creating intermolecular forces.
Statement IV is false. Not all polar molecules have hydrogen bonding. Hydrogen bonding occurs specifically between a hydrogen atom bonded to an electronegative atom (such as oxygen or nitrogen) and another electronegative atom. It is a stronger type of intermolecular force compared to other types of dipole-dipole interactions. So, not all polar molecules have hydrogen bonding.
Therefore, the statements I, II, and III are true, while statement IV is false. Hence, the correct answer is D: I, II, and III only.
To determine which statements are true, let's analyze each one and their correctness.
I. All polar molecules have dipole moments.
To check the correctness of this statement, we need to understand what a dipole moment is. A dipole moment is the measure of the polarity or asymmetry of a molecule. A polar molecule is one in which the charge distribution is uneven or asymmetric, resulting in a dipole moment. Therefore, it is true that all polar molecules have dipole moments.
II. All polar molecules have oppositely charged regions.
This statement is true. Polar molecules have an uneven distribution of charge, meaning they have both positively and negatively charged regions. This charge imbalance creates polarity in the molecule.
III. A polar molecule is attracted to other molecules because of electrostatic forces.
This statement is also true. Polar molecules have regions of positive and negative charge, and they can interact with other polar molecules or ions through electrostatic forces. These forces include dipole-dipole interactions and ion-dipole interactions.
IV. All polar molecules have hydrogen bonding.
This statement is not true. While hydrogen bonding is a type of intermolecular force that occurs in some polar molecules, not all polar molecules have hydrogen bonding. Hydrogen bonding specifically occurs between a hydrogen atom bonded to an electronegative atom (such as oxygen, nitrogen, or fluorine) and a lone pair of electrons on another electronegative atom.
Now, let's determine the correct answer based on the analysis above:
Statement I is true.
Statement II is true.
Statement III is true.
Statement IV is false.
The only answer choice that includes the three true statements is answer choice D: I, II, and III only.