Q: A sample of naturally occurring gallium has an average atomic mass of 69.7 and consists of two isotopes, gallium-69 and gallium-71. If the atomic masses are 68.9 amu and 70.9 amu respectively, which equation would you use to calculate the percent abundance of gallium-69?

$$69.7 = (x \times 68.9) + ((1-x) \times 70.9)$$

Q: Which of the following is the correct formula for calculating the number of neutrons in an atom?

$$\text{Number of neutrons} = \text{Mass number} - \text{Atomic number}$$

Q: Which equation would you use to convert Fahrenheit to Celsius?

$$^\circ C = (^\circ F - 32) \times \frac{5}{9}$$

Question 1

Which of the following best describes a homogeneous mixture?

Accepted Answer

A mixture that exhibits a uniform composition and appears visually the same throughout.

Question 2

Which physical state of matter is characterized by molecules that are widely separated and can move around freely?

Accepted Answer

Gas

Question 3

Which of the following is NOT a physical change?

Accepted Answer

Burning gasoline in a lawnmower

Question 4

A sample of naturally occurring gallium has an average atomic mass of 69.7 and consists of two isotopes, gallium-69 and gallium-71. If the atomic masses are 68.9 amu and 70.9 amu respectively, which equation would you use to calculate the percent abundance of gallium-69?

Accepted Answer

$$69.7 = (x 	imes 68.9) + ((1-x) 	imes 70.9)$$

Question 5

Which element is specified by the atomic number $$Z = 26$$?

Accepted Answer

Iron

Question 6

Which of the following pairs are isotopes of the same element?

Accepted Answer

$$^{12}_{6}Z$$ \, and \, ^{14}_{6}Z$

Question 7

Which of the following is a chemical change?

Accepted Answer

Burning a candle

Question 8

What is the correct conversion formula from Celsius to Kelvin?

Accepted Answer

$$K = ^\circ C + 273.15$$

Question 9

Which of the following elements is a metalloid?

Accepted Answer

Silicon

Question 10

Which element would have physical and chemical properties most similar to chlorine?

Accepted Answer

Bromine

Question 11

A mixture of oil and water is best classified as:

Accepted Answer

A heterogeneous mixture

Question 12

Which of the following statements about atoms is correct?

Accepted Answer

Atoms are composed of protons, neutrons, and electrons.

Question 13

Which group in the periodic table contains elements that are very reactive and exist as two atoms joined together?

Accepted Answer

Group 7A

Question 14

Which of the following is the correct formula for calculating the number of neutrons in an atom?

Accepted Answer

$$	ext{Number of neutrons} = 	ext{Mass number} - 	ext{Atomic number}$$

Question 15

Which of the following is a property of metals?

Accepted Answer

Good conductors of heat and electricity

Question 16

Which of the following is an example of a compound?

Accepted Answer

Water

Question 17

Which of the following describes the electron cloud in an atom?

Accepted Answer

Comprises most of the atom’s volume

Question 18

Which equation would you use to convert Fahrenheit to Celsius?

Accepted Answer

$$^\circ C = (^\circ F - 32) 	imes \frac{5}{9}$$

Question 19

Which of the following is a characteristic of a solid?

Accepted Answer

Has a definite shape and volume

Classification of Matter, States, and Atomic Structure: Study Notes for General, Organic, and Biological Chemistry

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