Question 1

Which of the following best describes a compound?

Accepted Answer

A substance composed of two or more elements chemically combined in a fixed ratio.

Question 2

Which of the following statements about the periodic table is correct?

Accepted Answer

Elements are arranged by increasing atomic number.

Question 3

A student measures the mass of a metal block as $$ 45.67 \ \mathrm{g} $$ and its volume as $$ 16.2 \ \mathrm{cm}^3 . $$What is the density of the block, reported with the correct number of significant figures?

Accepted Answer

$$ 2.82 \ \mathrm{g/cm}^3 $$

Question 4

Which of the following is an example of an ionic bond?

Accepted Answer

The bond between sodium and chlorine in $$ \mathrm{NaCl} $$

Question 5

Which SI unit would you use to measure the amount of a substance in a chemical reaction?

Accepted Answer

Mole

Question 6

A sample of gas has a mass of $$ 0.250 \ \mathrm{g} $$ and occupies a volume of $$ 125 \ \mathrm{mL} . $$What is its density in $$ \mathrm{g/mL} $$?

Accepted Answer

$$ 0.0020 \ \mathrm{g/mL} $$

Question 7

Which of the following best explains why water ($$ \mathrm{H}_2\mathrm{O} ) is $$considered a pure substance?

Accepted Answer

It has a fixed composition and distinct chemical properties.

Question 8

Which of the following statements about atoms is correct?

Accepted Answer

Protons and neutrons are found in the nucleus.

Question 9

A chemist needs to measure the temperature of a reaction. Which SI unit should be used?

Accepted Answer

Kelvin

Question 10

Which of the following is a property of a solid state of matter?

Accepted Answer

Particles are close together and vibrate in fixed positions.

Question 11

A student records the following measurements: $$ 12.0 \ \mathrm{g} $$, $$ 12.00 \ \mathrm{g} $$, and $$ 12 \ \mathrm{g} . $$Which measurement has the greatest number of significant figures?

Accepted Answer

$$ 12.00 \ \mathrm{g} $$

Question 12

Which of the following best describes a covalent bond?

Accepted Answer

A bond formed by the sharing of electron pairs between atoms.

Question 13

A hospital stores oxygen gas in a tank with a mass of $$ 32.0 \ \mathrm{kg} $$ and a volume of $$ 22.4 \ \mathrm{L} . $$What is the density of the oxygen gas in $$ \mathrm{kg/L} $$? (Round to two significant figures.)

Accepted Answer

$$ 1.4 \ \mathrm{kg/L} $$

Question 14

Which of the following is NOT an SI base unit?

Accepted Answer

Gram

Question 15

A sample of ethanol has a mass of $$ 78.5 \ \mathrm{g} $$ and a volume of $$ 100.0 \ \mathrm{mL} . $$What is its density in $$ \mathrm{g/mL} $$? (Report to three significant figures.)

Accepted Answer

$$ 0.785 \ \mathrm{g/mL} $$

Question 16

Which of the following best explains why carbon dioxide ($$ \mathrm{CO}_2 ) is $$classified as a compound?

Accepted Answer

It consists of two or more elements chemically combined in a fixed ratio.

Question 17

A student is asked to convert $$ 250 \ \mathrm{mL}  of $$water to liters using SI units. What is the correct answer?

Accepted Answer

$$ 0.25 \ \mathrm{L} $$

Question 18

Which of the following is a correct statement about significant figures?

Accepted Answer

All nonzero digits are significant.

Question 19

A patient receives a saline solution containing $$ 0.90 \ \mathrm{g}  of $$salt in $$ 100 \ \mathrm{mL}  of $$water. What is the density of the solution in $$ \mathrm{g/mL}  if $$the total mass of the solution is $$ 100.90 \ \mathrm{g} $$? (Round to three significant figures.)

Accepted Answer

$$ 1.01 \ \mathrm{g/mL} $$

Question 20

Which of the following best describes the difference between an element and a compound?

Accepted Answer

An element contains only one type of atom, while a compound contains two or more elements chemically combined.

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