1.
What is the structural formula of water? Please choose the closest answer
Correct Answer
C. H-O-H
Explanation
Water has a molecular formula of . Since hydrogen forms a single bond, and oxygen prefers to form two bonds, the most reasonable structural formula is H-O-H. Note that this shows each hydrogen atom with one bond, and oxygen with two bonds.
2.
Correct Answer
A. Molecular formula
Explanation
is the molecular formula for ethanol. This means that a molecule for ethanol has two carbon atoms, six hydrogen atoms, and one oxygen atom. However, it does not tell us how those molecules are collected- for that we need a structural formula. It does tell us that those nine atoms are bonded together to form a single substance.
3.
What is the relationship between the two substances shown below?
Correct Answer
C. Isomers
Explanation
The two molecules are isomers: they have the same molecular formulas (
4.
Magnesium hydroxide, present in milk of magnesia, has a molecular formula of , therefore each molecule of magnesium hydroxide contains ____ oxygen atoms
Correct Answer
B. 2
Explanation
The molecular formula tells us that there are two OH groups (known as hydroxide ions) attached to magnesium; in other words magnesium hydroxide has a structural formula of H-O-Mg-O-H. Therefore each mulecule contains two oxygen atoms.
5.
How many bonds does nitrogen typically form?
Correct Answer
C. 3
Explanation
Nitrogen typically forms 3 bonds. The mnemonic "HONC if you love chemistry" may help you remember the number of bonds for each of the four most common elements of life: H1, O2, N3, and C4.
6.
How many bonds does hydrogen typically form?
Correct Answer
A. 1
Explanation
Hydrogen typically forms 1 bond. The mnemonic "HONC if you love chemistry" may help you remember the number of bonds for each of the four most common elements of life: H1, O2, N3, and C4.
7.
How many bonds does oxygen typically form?
Correct Answer
B. 2
Explanation
Oxygen typically forms 2 bonds. The mnemonic "HONC if you love chemistry" may help you remember the number of bonds for each of the four most common elements of life: H1, O2, N3, and C4.
8.
How many bonds does carbon typically form?
Correct Answer
D. 4
Explanation
Carbon typically forms 4 bonds. The mnemonic "HONC if you love chemistry" may help you remember the number of bonds for each of the four most common elements of life: H1, O2, N3, and C4.
9.
H-O-H is an example of a ________ formula
Correct Answer
B. Structural
Explanation
H-O-H is the structural formula for water. Note that it provides the bonding arrangement for the molecular formula for water ()
10.
is the _____ formula for water.
Correct Answer
A. Molecular
Explanation
is the molecular formula for water. Note that it does not show how the atoms are arranged in space- for that you need the structural formula.
11.
What is the relationship between the two substances shown below?
Correct Answer
A. Isomers
Explanation
The two substances are isomers since they both have a molecular formula of but the the structural formulas are different- not how the "OH" group (known as a hydroxyl group) is on the end of one, and in the center on the other isomer.
12.
Substance A has a molecular formula of and substance B has a molecular formula of What is the relationship between substance A and substance B?
Correct Answer
B. They are not isomers- they are each completely different substances
Explanation
Substances A and B cannot be isomers because they have different molecular formulas. Isomers have the same molecular formulas but different arrangements of the atoms.
13.
What is wrong with the substance
Correct Answer
B. It is unlikely to exist because carbon can only form 4 bonds
Explanation
The substance is unlikely to exist since carbon can only form four bonds; CH4 is a common substance known as methane. There are no isomers for CH5 since it does not exist.
14.
Which of the following substances are organic?a. NaCl, commonly known as table saltb. , commonly known as methanec. , commonly known as sulfuric acidd. Au, commonly known as golde. , which may be ethanol or dimethyl ether, depending on the isomer
Correct Answer
A. Substances B and E are organic
Explanation
Substances B and E are organic since they contain carbon.
Either isomer for E is organic since both contain carbon.
This question is using the scientific meaning of the term organic. Farmers and vegans may have a different definition of the term "organic".
15.
Which of the following is true about
Correct Answer
C. It is the molecular formula for an organic substance
Explanation
This is a molecular formula since the bonds are not explicitly shown. It is an organic substance since it contains carbon. Note that in this particular case there is only one isomer possible. Often a molecular formula can be the basis for multiple isomers, but in this case it can only be assembled one way while mainitaining four bonds for carbon, two for oxygen, and one for each hydrogen: