Question 1

Which of the following statements best describes a chemical change?

Accepted Answer

A compound decomposes into its constituent elements when heated.

Question 2

A sample contains 0.025 kg of a substance. How many grams does this represent? Use the metric conversion factor $$1 \mathrm{kg} = 1000 \mathrm{g}.$$

Accepted Answer

$$25 \mathrm{g}$$

Question 3

Which of the following is a heterogeneous mixture?

Accepted Answer

Oil and water

Question 4

A student measures the mass of a liquid as $$12.50 \mathrm{g}$$ and its volume as $$8.0 \mathrm{mL}. $$What is the density of the liquid? Use $$	ext{Density} = \frac{	ext{mass}}{	ext{volume}}.$$

Accepted Answer

$$1.56 \mathrm{g/mL}$$

Question 5

Which of the following best describes an isotope?

Accepted Answer

Atoms of the same element with different numbers of neutrons.

Question 6

Which of the following elements is most likely to form a cation?

Accepted Answer

Sodium

Question 7

How many significant figures are in the measurement $$0.00450$$?

Accepted Answer

3

Question 8

Which of the following best describes the arrangement of particles in a solid?

Accepted Answer

Particles are closely packed in a fixed, orderly arrangement.

Question 9

A patient receives an IV solution containing $$0.9\%$$ NaCl. What is the mass of NaCl in $$250 \mathrm{mL} of $$solution? (Assume density is $$1.0 \mathrm{g/mL})$$

Accepted Answer

$$2.25 \mathrm{g}$$

Question 10

Which of the following is the correct scientific notation for $$0.000125$$?

Accepted Answer

$$1.25 	imes 10$$^{-4}$$

Question 11

Which statement about the periodic table is correct?

Accepted Answer

Periods are horizontal rows and groups are vertical columns.

Question 12

What is the number of valence electrons in an atom of sulfur ($$	ext{Group Number} = 16$$)?

Accepted Answer

6

Question 13

Which of the following is a physical change?

Accepted Answer

Melting of ice.

Question 14

A compound contains 2 atoms of hydrogen and 1 atom of oxygen. What is its chemical formula?

Accepted Answer

$$\mathrm{H}_2\mathrm{O}$$

Question 15

Which of the following best describes an ionic bond?

Accepted Answer

A bond formed by the transfer of electrons from a metal to a nonmetal.

Question 16

Which of the following is a correct Lewis symbol for magnesium ($$\mathrm{Mg}$$)?

Accepted Answer

$$\mathrm{Mg}\cdot\cdot$$

Question 17

A food contains $$200 \mathrm{Cal} ($$kilocalories). How many joules does this represent? ($$1 \mathrm{Cal} = 4184 \mathrm{J})$$

Accepted Answer

$$836,800 \mathrm{J}$$

Question 18

Which of the following is a covalent compound?

Accepted Answer

$$\mathrm{CO}_2$$

Question 19

Which of the following is NOT a property of metals?

Accepted Answer

Brittle

Question 20

Which of the following statements about electrolytes is correct?

Accepted Answer

Electrolytes are compounds that dissociate into ions in water.

GOB Chemistry Study Notes: Measurement, Matter, Atomic Structure, and Chemical Bonding

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