AnswersNC-Physical Science Fall 1st 9 WeeksCovalent Bonds

Covalent Bonds — Unit test Answers

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1
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Which term best describes all atoms in ionic bonds?

A
stable
B
unstable
C
positively charged
D
negatively charged
2
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How do the nuclei of covalently bonded atoms help keep the bond together?

A
Neutral particles in the nucleus provide enough mass that the force of gravity holds the atoms together.
B
Neutral particles in the nucleus can become positive or negative in order to balance the charges.
C
Positive particles in the nucleus change into negative particles that enter electron shells.
D
Positive particles in the nucleus are attracted to shared electrons, so the atoms stay close together.
3

Giovanni created this chart to study for an exam.Which best describes how to correct the error in the chart?

Question illustration
A
Remove “plastics” from the uses for sodium hydroxide.
B
Swap the uses for iron oxide and calcium carbonate.
C
Change the use for calcium chloride to “used in preservatives.”
D
Add “de-ice roads” to uses for calcium carbonate.
4

Which element has fewer than four dots in its electron dot diagrams?

A
arsenic (As)
B
sulfur (S)
C
krypton (Kr)
D
gallium (Ga)
5

What causes an ionic bond to form between sodium and chlorine?

A
Sodium and chlorine atoms share electrons.
B
Sodium and chlorine atoms switch electrons.
C
Sodium atoms gain electrons.
D
Sodium atoms donate electrons.
6

Fluorine has an atomic number 9. It is in period 2 of the periodic table. The diagram shows the electron dot diagram of a fluorine atom.

Question illustration
A
two
B
seven
C
nine
D
seventeen
7

Lionel has a hot plate, a thermometer, a container of water, a spoon, and a small hammer. Using these tools, Lionel can test several properties of an ionic compound.Which property of the compound will he not be able to test?

A
atomic structure
B
melting point
C
ability to dissolve
D
brittleness
8

Which element is least likely to form chemical bonds?

A
phosphorus (P)
B
helium (He)
C
sodium (Na)
D
carbon (C)
9

How many atoms of each element are in the chemical formula NH4NO3?

A
1 nitrogen, 1 hydrogen, and 3 oxygen
B
1 nitrogen, 4 hydrogen, and 3 oxygen
C
2 nitrogen, 4 hydrogen, and 3 oxygen
D
5 nitrogen, 1 hydrogen, and 1 oxygen
10

Suna passes an electric current through a sample of clear, colorless, and odorless liquid. As the experiment continues, bubbles form, and the volume of liquid decreases. Suna collects samples of two colorless, odorless gases that bubble out of the liquid. One of the gases burns. Neither the original liquid nor the other gas burns.Which is the best explanation of her results?

A
The electric current changed some of the sample to gas even though the sample was not breaking down. Therefore, the original liquid is a compound.
B
The electric current released a gas that was odorless and colorless, like the original sample. Therefore, the original liquid is an element.
C
The sample was broken down by the electric current and formed a new substance that could burn. Therefore, the original liquid is a compound.
D
The sample lost some of its volume, but the gas still had the same chemical makeup as the original sample. Therefore, the original liquid is an element.
11

Which is the only element in group 1 on the periodic table that forms covalent bonds?

A
hydrogen
B
lithium
C
potassium
D
sodium
12

Formaldehyde is an organic compound. Each molecule includes two hydrogen (H) atoms, one oxygen (O) atom, and one carbon (C) atom. Below are the dot structures for each of these elements.Which diagram shows how the covalent bonds most likely form in a formaldehyde molecule?

Question illustration
A
Option
B
Option
C
Option
D
Option
13

The element sulfur (S) is most likely to form covalent bonds with the element

A
helium (He).
B
magnesium (Mg).
C
zinc (Zn).
D
oxygen (O).
14

Atoms of iron (Fe) form metallic bonds with other iron atoms. How are the valence electrons of these atoms rearranged to form the bonds?

A
A few valence electrons are shared between the atoms.
B
Many valence electrons are shared between the atoms.
C
Electrons are transferred from the iron atoms to atoms in the air.
D
Electrons are transferred to the iron atoms from atoms in the air.
15

What is a limitation of using a chemical formula, such as C6H12O6, to represent a compound?

A
The chemical formula does not show the types of elements that make up the compound.
B
The chemical formula does not show how the atoms are connected to one another.
C
The chemical formula does not show the number of atoms of each element in a molecule.
D
The chemical formula does not show the chemical symbols of the elements in the compound.

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