Question 1

Which statement about molecular formulas and molecular structures is INCORRECT?

Accepted Answer

Molecular structure cannot be used to calculate molecular weight.

Question 2

What information does a structural formula provide that a molecular formula does NOT?

Accepted Answer

How atoms are connected to each other.

Question 3

Given the molecular formula $$\mathrm{C_2H_6O}$$, which of the following is TRUE?

Accepted Answer

It does not indicate how atoms are connected.

Question 4

Which formula is best used to calculate the molecular weight of a compound?

Accepted Answer

Molecular formula

Question 5

Why are molecular formulas insufficient for organic compounds?

Accepted Answer

They do not convey connectivity and orientation.

Question 6

Which of the following best describes a Lewis formula?

Accepted Answer

It shows how atoms are connected and includes lone pairs.

Question 7

Propane ($$\mathrm{C_3H_8}) is a $$component of liquefied petroleum gas. How many hydrogen atoms are bonded to the central carbon in its structural formula?

Accepted Answer

Two

Question 8

Which statement about the structural formula of methylamine ($$\mathrm{CH_3NH_2}) is $$correct?

Accepted Answer

The nitrogen atom is bonded to two hydrogen atoms and one carbon atom.

Question 9

Which of the following is a key difference between Lewis and structural formulas?

Accepted Answer

Lewis formulas show lone pairs, while structural formulas do not.

Question 10

A student draws the following for $$\mathrm{C_2H_6O}$$: $$\mathrm{CH_3CH_2OH}. $$What type of formula is this?

Accepted Answer

Structural formula

Question 11

Which of the following molecules can have more than one structural formula but the same molecular formula?

Accepted Answer

$$\mathrm{C_2H_6O}$$

Question 12

If a compound has the molecular formula $$\mathrm{C_3H_8}$$, which of the following is TRUE about its structure?

Accepted Answer

Each carbon atom must have four bonds.

Question 13

Which formula would you use to determine the number of lone pairs on an atom in a molecule?

Accepted Answer

Lewis formula

Question 14

A student claims that the molecular formula $$\mathrm{C_2H_6O} is $$sufficient to determine the boiling point of the compound. Why is this incorrect?

Accepted Answer

Boiling point depends on how atoms are connected, which is not shown by the molecular formula.

Question 15

Which of the following is NOT shown in a structural formula?

Accepted Answer

Lone pairs on atoms.

Question 16

Which formula would you use to determine the connectivity of atoms in a molecule?

Accepted Answer

Structural formula

Question 17

Which of the following statements is TRUE regarding the orientation of atoms in a molecule?

Accepted Answer

Neither molecular nor structural formulas show the orientation of atoms.

Question 18

Which formula is most useful for predicting the reactivity of a molecule?

Accepted Answer

Structural formula

Question 19

A patient is exposed to methylamine ($$\mathrm{CH_3NH_2}). $$Which formula would help a chemist understand how the atoms are connected in this molecule?

Accepted Answer

Structural formula

Question 20

Which of the following is a limitation of the molecular formula?

Accepted Answer

It does not show how atoms are connected.

Molecular and Structural Representations in Organic Chemistry

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