$$250.0\ \mathrm{mL} \times \frac{1\ \mathrm{L}}{1000\ \mathrm{mL}} = 0.2500\ \mathrm{L}$$

$$500\ \mathrm{Cal} \times 4.184\ \mathrm{kJ/Cal} \times 1000\ \mathrm{J/kJ} = 2,092,000\ \mathrm{J}$$

Question 1

Which of the following best describes a heterogeneous mixture?

Accepted Answer

A mixture in which the components are not evenly distributed, such as oil and water.

Question 2

A sample of a metal has a mass of 45.0 g and a volume of 15.0 mL. What is its density?

Accepted Answer

$$\frac{45.0\ \mathrm{g}}{15.0\ \mathrm{mL}} = 3.0\ \mathrm{g/mL}$$

Question 3

Which of the following is a chemical change?

Accepted Answer

Burning wood in a fireplace.

Question 4

How many significant figures are in the measurement 0.004560?

Accepted Answer

5

Question 5

Convert 250.0 milliliters (mL) to liters (L).

Accepted Answer

$$250.0\ \mathrm{mL} 	imes \frac{1\ \mathrm{L}}{1000\ \mathrm{mL}} = 0.2500\ \mathrm{L}$$

Question 6

Which of the following statements about isotopes is correct?

Accepted Answer

Isotopes of an element have the same number of protons but different numbers of neutrons.

Question 7

A neutral atom of chlorine has an atomic number of 17 and a mass number of 35. How many neutrons does it have?

Accepted Answer

$$35 - 17 = 18$$ neutrons

Question 8

Which of the following best describes the trend in atomic radius across a period in the periodic table?

Accepted Answer

Atomic radius decreases from left to right across a period.

Question 9

Which of the following ions has the same number of electrons as a neutral atom of neon ($$Z=10$$)?

Accepted Answer

$$\mathrm{Na}^+$$

Question 10

Which of the following is the correct electron configuration for a neutral atom of carbon ($$Z=6$$)?

Accepted Answer

$$1s^2$$\ $$2s^2$$\ $$2p^2$$

Question 11

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 12

Which of the following is a correct Lewis symbol for a sodium ion ($$\mathrm{Na}^+$$)?

Accepted Answer

$$\mathrm{Na}^+$$

Question 13

Which of the following is a property of metals?

Accepted Answer

They are malleable and ductile.

Question 14

A patient receives 500 Calories (Cal) from a meal. How many joules (J) is this equivalent to? ($$1\ \mathrm{Cal} = 4.184\ \mathrm{kJ})$$

Accepted Answer

$$500\ \mathrm{Cal} 	imes 4.184\ \mathrm{kJ/Cal} 	imes 1000\ \mathrm{J/kJ} = 2,092,000\ \mathrm{J}$$

Question 15

Which of the following best explains why noble gases are generally unreactive?

Accepted Answer

They have a full valence shell of electrons.

Question 16

Which of the following is the correct formula for magnesium chloride?

Accepted Answer

$$\mathrm{MgCl}_2$$

Question 17

Which of the following statements about electrolytes is correct?

Accepted Answer

Electrolytes are substances that conduct electricity when dissolved in water.

Question 18

Which of the following best describes the law of conservation of mass?

Accepted Answer

Mass is neither created nor destroyed in a chemical reaction.

Question 19

Which of the following is a correct statement about valence electrons?

Accepted Answer

Valence electrons are the electrons in the outermost shell of an atom.

Question 20

A compound contains 40.0% carbon, 6.7% hydrogen, and 53.3% oxygen by mass. What is the empirical formula of the compound?

Accepted Answer

$$\mathrm{CH}_2\mathrm{O}$$

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

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