1
.
What is the term for atoms of the same element that vary in the number of neutrons in their nuclei?
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ions
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isotopes
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isobars
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neutral atoms
2
.
Potassium has an atomic number of 19. What is its electron configuration?
-
Shells 1 and 2 are full, and shell 3 has nine electrons.
-
Shells 1, 2, and 3 are full, and shell 4 has three electrons.
-
Shells 1, 2, and 3 are full, and shell 4 has one electron.
-
Shells 1, 2, and 3 are full, and no other electrons are present.
3
.
Which type of bond exemplifies a weak chemical bond?
-
covalent bonds in solution
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hydrogen bonds in solution
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ionic bonds in solids
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nonpolar covalent bonds in solids
4
.
Which of the following statements is false?
-
Electrons are unequally shared in polar covalent bonds.
-
Electrons are equally shared in nonpolar covalent bonds.
-
Hydrogen bonds are weak bonds based on electrostatic forces.
-
In solution, ionic bonds are generally stronger than covalent bonds.
5
.
If xenon has an atomic number of and a mass number of , how many neutrons does it have?
6
.
What forms ionic bonds?
-
atoms that share electrons equally
-
atoms that share electrons unequally
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ions with similar charges
-
ions with opposite charges
7
.
Based on the information provided in the table, which of the following statements is correct?
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In NH3, the nitrogen atom carries a partial positive charge and the hydrogen atoms acquire a partial negative charge.
-
In H2O, the hydrogen atoms acquire a partial negative charge, and the oxygen atom carries a partial positive charge.
-
In aqueous HCl, the hydrogen atom carries a partial positive charge, and the chlorine atom carries a partial negative charge.
-
In LiF, the lithium atom carries a positive charge, and the fluorine atom carries a negative charge.
8
.
Which of the following statements is not true?
-
Water is polar.
-
Water can stabilize the temperature of nearby air.
-
Water is essential for life.
-
Water is the most abundant molecule in the Earth’s atmosphere.
9
.
Explain why the bonds within a water molecule are described as polar covalent bonds.
-
Hydrogen is more electronegative than oxygen, generating a partial negative charge near the hydrogen atom.
-
Hydrogen is more electronegative than oxygen, generating a partial positive charge near the hydrogen atom.
-
Oxygen is more electronegative than hydrogen, generating a partial negative charge near the oxygen atoms.
-
Oxygen is more electronegative than hydrogen, generating a partial positive charge near the oxygen atoms.
10
.
What happens to the pH of a solution when acids are added?
-
The pH of the solution decreases.
-
The pH of the solution increases.
-
The pH of the solution increases and then decreases.
-
The pH of the solution stays the same.
11
.
Which of the following statements is true?
-
Acids and bases cannot mix together.
-
Acids and bases can neutralize each other.
-
Acids, not bases, can change the pH of a solution.
-
Acids donate hydroxide ions (); bases donate hydrogen ions ().
12
.
Define water’s property of adhesion.
-
a force that allows surface water molecules to escape and vaporize
-
the attraction between water molecules and other molecules
-
the intermolecular force between water molecules
-
the force that keeps particles dispersed in water
13
.
How are excess hydrogen ions balanced in a solution?
-
acid
-
base
-
donator
-
isotope
14
.
What is the maximum number of atoms or molecules a single carbon atom can bond with?
-
4
-
1
-
6
-
2
15
.
Which of the following statements is true?
-
Molecules with the formulas and could be structural isomers.
-
Cis-trans isomers are arranged about a single bond.
-
To be enantiomers, a pair of molecules must have at least three different atoms or groups connected to a central carbon, but arranged differently.
-
To be enantiomers, a pair of molecules must have four different atoms or groups connected to a central carbon, but arranged differently.
16
.
Which of the following is least likely to bond with carbon as a functional group in biological systems?
-
carbonyl
-
hydroxyl
-
phosphate
-
sodium
17
.
Which of the following functional groups is the least polar?
-
carbonyl
-
hydroxyl
-
methyl
-
sulfhydryl
18
.
What are enantiomers?
-
hydrocarbons consisting of closed rings of carbon atoms
-
structural isomers differing in placement of atoms along a carbon-carbon double bond
-
molecules sharing the same chemical bonds but are mirror images of each other
-
molecules with the same chemical formula but different placement of their chemical bonds