Question 1

Which of the following best describes a chemical, according to the definition used in chemistry?

Accepted Answer

Any substance that has a definite composition and distinct properties.

Question 2

A student measures the mass of a sample as 0.004560 g. How many significant figures does this measurement have?

Accepted Answer

$$5$$

Question 3

Which of the following is the correct scientific notation for the number $$0.000378$$?

Accepted Answer

$$3.78 	imes 10$$^{-4}$$

Question 4

A sample of gold has a mass of $$96.5\ \mathrm{g}$$ and a volume of $$5.00\ \mathrm{cm}^3. $$What is the density of gold, rounded to the correct number of significant figures?

Accepted Answer

$$19.3\ \mathrm{g/cm}^3$$

Question 5

Which of the following statements about the three states of matter is correct?

Accepted Answer

Gases have neither a definite shape nor a definite volume.

Question 6

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

Accepted Answer

Burning of wood

Question 7

A student converts $$25.0\ ^\circ\mathrm{C} to $$Kelvin. What is the correct value, rounded to the proper number of significant figures?

Accepted Answer

$$298\ \mathrm{K}$$

Question 8

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

Accepted Answer

Compounds are made of two or more elements chemically combined in a fixed ratio.

Question 9

Which of the following is a correct application of the rules for significant figures in the calculation $$4.56 + 1.4$$?

Accepted Answer

$$6.0$$

Question 10

A patient receives $$250.0\ \mathrm{mg} of a $$medication. How many grams is this? (Use $$1\ \mathrm{g} = 1000\ \mathrm{mg}$$ and round to the correct number of significant figures.)

Accepted Answer

$$0.250\ \mathrm{g}$$

Question 11

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

Accepted Answer

Groups are vertical columns and periods are horizontal rows.

Question 12

Which of the following best describes the difference between kinetic and potential energy?

Accepted Answer

Kinetic energy is energy of motion, while potential energy is stored energy.

Question 13

Which of the following is the correct electron configuration for a neutral atom of oxygen ($$Z=8$$)?

Accepted Answer

$$1s^2$$\ $$2s^2$$\ $$2p^4$$

Question 14

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 15

Which of the following best explains why sodium ($$\mathrm{Na}) $$forms a $$+1$$ ion?

Accepted Answer

Sodium loses one electron to achieve a noble gas configuration.

Question 16

Which of the following best describes a polar covalent bond?

Accepted Answer

A bond in which electrons are shared unequally between two atoms due to a difference in electronegativity.

Question 17

Which of the following molecules is non-polar?

Accepted Answer

$$\mathrm{CO}_2$$

Question 18

A $$50.0\ \mathrm{g}$$ sample of water is heated from $$20.0\ ^\circ\mathrm{C} to$$ $$30.0\ ^\circ\mathrm{C}. If $$the specific heat capacity of water is $$4.18\ \mathrm{J/g\cdot ^\circ C}$$, how much energy is absorbed? (Use $$q = m c \Delta T$$ and round to the correct number of significant figures.)

Accepted Answer

$$2090\ \mathrm{J}$$

Question 19

Which of the following statements about the Bohr and Quantum-Mechanical models of the atom is correct?

Accepted Answer

The Bohr model describes electrons in fixed orbits, while the Quantum-Mechanical model describes electrons in orbitals with probabilities of location.

Question 20

Which of the following best describes the octet rule?

Accepted Answer

Atoms tend to gain, lose, or share electrons to achieve eight electrons in their outermost shell.

Introductory Chemistry Midterm Study Guide – Step-by-Step Guidance

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