QUESTION 1

Which of the following is an accurate description of a theory?

a well-tested explanation for how something works.

an observation made over and over again.

someone’s idea about how something works.

easily proved wrong and therefore cannot be trusted in science.

3 points Save Answer

QUESTION 2

Which of following statements is true about scientific knowledge?

Scientific ideas are not subject to change, and so knowledge stays the same.

Scientific knowledge is constantly evolving as new observations are made.

While scientific knowledge increases over time, old knowledge never changes.

Theories can change frequently, but scientific knowledge is absolute.

3 points Save Answer

QUESTION 3

Which of the following is an example of pure research?

Determining the causes of dementia in elderly people.

Creating robots to walk on the surface of Mars.

Colliding subatomic particles at high speeds to see what they form.

Working with alloys to determine the lightest carbon fiber composition for armor.

3 points Save Answer

QUESTION 4

Which of the following institutions employs scientists?

Hospitals

Universities

Corporations

All of the above

3 points Save Answer

QUESTION 5

If the flame of a Bunsen burner should accidentally go out, a student should immediately run over to the teacher and inform him/her.

TRUE

FALSE

2 points Save Answer

QUESTION 6

In terms of eye safety in the lab:

Students do not need to wear safety goggles if they already have prescription glasses on.

Students need to wear safety goggles at all times, regardless if they have prescription glasses or not.

Students only need to wear safety goggles if they do not have their own prescription glasses or if they have contacts.

Goggles only need to be worn if the chemicals used in a lab are liquids or solutions.

3 points Save Answer

QUESTION 7

You observe that a liquid has decreased volume by 23.4 milliliters (mL) during the duration of an experiment. What is this type of observation?

quantitative

qualitative

indirect observation

a physical change

3 points Save Answer

QUESTION 8

It is equally accurate to measure volumes with a beaker as with a graduated cylinder.

TRUE

FALSE

2 points Save Answer

QUESTION 9

When measuring the volume of a liquid in a graduated cylinder, you should raise the cylinder up to eye level to read the meniscus more accurately.

TRUE

FALSE

2 points Save Answer

QUESTION 10

To accurately measure the volume of a typical liquid in a graduated cylinder, what should you do?

look at the bottom part of the meniscus

look at the top part of the meniscus

average the top and bottom parts of the meniscus

ignore the meniscus and determine which mL line the liquid is closest to

3 points Save Answer

QUESTION 11

To accurately measure out 35 milliliters of liquid, you should use:

a 10-mL glass pipette several times

a 50-mL beaker

a 25-mL graduated cylinder two times

a 50-mL graduated cylinder one time

3 points Save Answer

QUESTION 12

Two groups complete an experiment requiring the mass measurement to be repeated three times in the experiment. Group I selects a single member of the group to measure the mass. Group II allows any person of the group to measure the mass once, so they will be done more quickly. At the end of the experiment, the results for group I are closer to the actual than the results of group II. Explain why this might be.

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5 points Save Answer

QUESTION 13

Which of the following would be considered the most heterogeneous mixture?

oil/vinegar salad dressing

pasteurized milk

vinegar

olive oil

3 points Save Answer

QUESTION 14

Which of the following pairs forms a homogenous mixture after being mixed together?

sand and water

salt and water

oil and water

oil and vinegar

3 points Save Answer

QUESTION 15

Which of the following is an example of a physical change?

Rusting bicycle chain

Melting butter

Fireworks exploding

Baking a cake

3 points Save Answer

QUESTION 16

Which of the following is an example of a physical change?

Separating sand from gravel

Baking a pie

Burning a piece of paper

Rusting

3 points Save Answer

QUESTION 17

Of the following examples, select those that represent a chemical change.I. Water freezing and changing into iceII. Leaves changing color in the fallIII. Mixing lemonade mix powder with waterIV. Milk going sour

II, III, IV

I, II, III, IV

II, IV

I, II

3 points Save Answer

QUESTION 18

Which of the following is an example of a chemical property?

Flammability

Boiling point

Density

Elasticity

3 points Save Answer

QUESTION 19

A mixture of sand and iron filings can be separated into its individual components by using a magnet.

TRUE

FALSE

2 points Save Answer

QUESTION 20

Which of the following is NOT a method used to physically separate components in a mixture?

chromatography

sublimation

distillation

precipitation

3 points Save Answer

QUESTION 21

The best way to separate ethanol from its solution in water is to use which of the following?

chromatography

precipitation

distillation

filtration

3 points Save Answer

QUESTION 22

The standard (Bohr) model of the atom shows that:

a positively charged nucleus has negatively charged particles surrounding it

a neutrally charged nucleus has neutrally charge particles encompassing it

a negatively charged nucleus has positively charged particles encompassing it

a positively charged nucleus has positive or negatively charged particles encompassing it

3 points Save Answer

QUESTION 23

An atom has no electrical charge because:

its subatomic particles have no electrical charges

the positively charged neutrons cancel out the negatively charged electrons

the negatively charged neutrons cancel out the positively charged protons

there are as many positively charged protons as negatively charged electrons

3 points Save Answer

QUESTION 24

The atomic number represents the total number of protons and neutrons in an atom.

TRUE

FALSE

2 points Save Answer

QUESTION 25

Electrons exist only outside of the nucleus.

TRUE

FALSE

2 points Save Answer

QUESTION 26

Pick the correct statement for the following isotope: 42Ca

42 is the mass number and 20 is the atomic number.

42 is the number of neutrons and 20 is the number of protons.

42 is the number of protons and 20 is the number of electrons.

42 is the atomic number and 20 is the number of neutrons.

3 points Save Answer

QUESTION 27

In structure, the standard (Bohr) model of the atom is most similar to

plum pudding

our solar system

chocolate chip cookie dough

the Milky Way galaxy

3 points Save Answer

QUESTION 28

Most of the volume of an atom is contained:

in the protons

in the nucleus

in the neutrons

in the empty space around the nucleus

3 points Save Answer

QUESTION 29

In comparing two isotopes of the same element, the atomic number:

changes to reflect the number of protons.

changes to reflect the new mass number.

changes to reflect the number of new neutrons.

stays the same.

3 points Save Answer

QUESTION 30

If the number of protons for an element changes, then:

the element turns into an isotope

the element becomes a different element

the number of electrons for that element changes as well

the number of neutrons changes as well

3 points Save Answer

QUESTION 31

Use the information for the isotopes of element X to calculate the average atomic mass of X, and identify the element.

Isotope Abundance Mass (amu)

35X 75.77% 34.969

37X 24.23% 36.965

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5 points Save Answer

QUESTION 32

Which of the following statements about subatomic particles best characterizes protons?

positive charge, heavy, found in the nucleus of an atom

no charge, heavy, found in the nucleus of an atom

negative charge, light, circling the nucleus of an atom

no charge, light, circling the nucleus of an atom

3 points Save Answer

QUESTION 33

Henry Moseley determined that, with a few exceptions, the order of increasing atomic number is the same as increasing atomic mass.

TRUE

FALSE

2 points Save Answer

QUESTION 34

Who was the first person to organize the elements so that properties of undiscovered elements could be predicted?

J.W. Dobereiner

Dmitri Mendeleev

JJ Thomson

Ernest Rutherford

3 points Save Answer

QUESTION 35

Generally, when going from left to right across a period on the periodic table:

atomic radii decrease

ionic radii increase

electronegativity decreases

valence electron number decreases

3 points Save Answer

QUESTION 36

In the periodic table, alkali metals are situated:

At the extreme left side.

At the extreme right side.

Towards the middle of the periodic table.

Directly next to the right of the stair steps/metalloids.

3 points Save Answer

QUESTION 37

Generally, when going down columns 1 or 2 of the periodic table, the reactivity of elements:

increases

decreases

remains the same except for noble gases

remains the same except for halogens

3 points Save Answer

QUESTION 38

Which of the following classifications is NOT correct?

Group 1 and Group 2 – Metals

Group 7 – Halogens

Group 8 – Noble Gases

Group 5 – Metalloids

3 points Save Answer

QUESTION 39

Which of the following classifications is NOT correct?

Noble gases – 8 valence electrons

Halogens – 6 valence electrons

Transition metals – number of valence electrons varies

Alkali Rare Earth metals – 2 valence electrons

3 points Save Answer

QUESTION 40

The chemical symbol for lead is La.

TRUE

FALSE

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