AnswersChemistry - SC3210 A-CRLab: Ionic and Covalent Bonds

Lab: Ionic and Covalent Bonds — Unit test Answers

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1
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Which statement best describes the difference between endothermic and exothermic reactions?

A
They are opposites because endothermic reactions require energy and exothermic reactions release energy.
B
They are opposites because endothermic reactions release energy and exothermic reactions require energy.
C
They the same because they are both ways of forming precipitates.
D
They the same because they are both ways of forming gasses.
2
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Which represents an endothermic reaction?

A
wood burning in a fire
B
splitting a gas molecule
C
using a heat pack on an injury
D
TNT exploding
3

Ciara’s bike has rusted, which means that the iron in the metal changed to rust.

A
an energy formation
B
an exothermic reaction
C
a chemical reaction
D
a precipitate formation
4

Nio conducts a science experiment. He puts yeast into a bottle with water and sugar, and then caps the bottle with a balloon. He returns two hours later and notices there are bubbles on the surface of the mixture in the bottle and that the balloon has inflated, but there are no other apparent changes.

A
a non-chemical change, because there are no indicators of chemical changes taking place
B
a chemical change, because the mixture changed color
C
a chemical change, because a gas was produced
D
a non-chemical change, because the changes that occurred are reversible
5

Which term best describes all atoms in ionic bonds?

A
stable
B
unstable
C
positively charged
D
negatively charged
6

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.
7

Which statement best describes balancing equations and the law of conservation of mass?

A
There are more atoms in the reactants than in the products, and the total mass is the same in the reactants and in the products.
B
The number of atoms is the same in the reactants and in the products, and the total mass is the same in the reactants and in the products.
C
There are fewer atoms in the reactants than in the products, and the total mass is less in the reactants than in the products.
D
There are more atoms in the reactants than in the products, and the total mass is higher in the reactants than in the products.
8

Lars is balancing equations with his study group. He is unsure about one equation because each member of the study group came up with a different answer. Which is the proper way to balance the equation Ca(OH)2 + H3PO4 → Ca3(PO4)2 + H2O?

A
Ca(OH)2 + H3PO4 → Ca3(PO4)2 + 6H2O
B
3Ca(OH)2 + 2H3PO4 → Ca3(PO4)2 + 6H2O
C
3Ca(OH)2 + 2H3PO4 → Ca3(PO4)2 + 3H2O
D
Ca(OH)2 + 2H3PO4 → Ca3(PO4)2 + 6H2O
9

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).
10

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.
11

What else is produced during the replacement reaction of magnesium and hydrochloric acid?Mg + 2HCl H2 + ________

Question illustration
A
MgCl2
B
Mg2Cl2
C
Mg2Cl
D
MgCl
12

Which type of reaction is Mg + S → MgS?

A
polymerization
B
synthesis
C
replacement
D
decomposition
13

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
14

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

A
hydrogen
B
lithium
C
potassium
D
sodium
15

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.

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