Q: Which of the following is the correct equation for calculating the atomic mass of chlorine given the following data: $$\mathrm{Cl}-35 (75.77$$%, 34.97 amu) and $$\mathrm{Cl}-37 (24.23$$%, 36.97 amu)?

$$\text{Atomic mass} = (0.7577 \times 34.97) + (0.2423 \times 36.97)$$

Q: Which of the following is the correct relationship for the mole concept?

$$\text{Number of entities} = \text{moles} \times 6.022 \times 10$$^{23}$$

Question 1

Which of the following best describes a 14-carat gold ring based on the classification of matter?

Accepted Answer

A homogeneous mixture

Question 2

Which of the following is a pure substance that cannot be separated into simpler substances by chemical means?

Accepted Answer

An element

Question 3

A sample of wet sand is best classified as which type of matter?

Accepted Answer

A heterogeneous mixture

Question 4

Which of the following statements is NOT a postulate of Dalton’s Atomic Theory?

Accepted Answer

Atoms of one element can change into atoms of another element during a chemical reaction.

Question 5

Which experiment led to the discovery that most of the atom’s mass is concentrated in a small, positively charged nucleus?

Accepted Answer

Rutherford’s gold foil experiment

Question 6

A neutral atom of sodium-23 ($$^{23}_{11}\mathrm{Na}) $$contains how many protons, neutrons, and electrons?

Accepted Answer

11 protons, 12 neutrons, 11 electrons

Question 7

Which of the following is the correct equation for calculating the atomic mass of chlorine given the following data: $$\mathrm{Cl}-35 (75.77$$%, 34.97 amu) and $$\mathrm{Cl}-37 (24.23$$%, 36.97 amu)?

Accepted Answer

$$	ext{Atomic mass} = (0.7577 	imes 34.97) + (0.2423 	imes 36.97)$$

Question 8

Which of the following best describes the composition of air in a sealed vial (78% $$\mathrm{N}_2$$, 21% $$\mathrm{O}_2$$)?

Accepted Answer

A homogeneous mixture

Question 9

How many $$\muL $$are there in 3.00 mL?

Accepted Answer

3.00 	imes $$10^3$$ $$\muL$$

Question 10

Which of the following is true about isotopes?

Accepted Answer

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

Question 11

A $$\mathrm{Se}^{2-}$$ ion has how many electrons?

Accepted Answer

36

Question 12

Which of the following best describes tea with sugar (after the sugar is dissolved)?

Accepted Answer

A homogeneous mixture

Question 13

Which of the following is NOT a part of Rutherford’s nuclear theory?

Accepted Answer

Electrons are embedded within a sphere of positive charge.

Question 14

Which of the following is a correct statement about ions?

Accepted Answer

Cations are positively charged ions formed by losing electrons.

Question 15

A sample contains only one type of particle, which cannot be separated into simpler substances. Which classification best fits this sample?

Accepted Answer

Element

Question 16

Which of the following is the correct relationship for the mole concept?

Accepted Answer

$$	ext{Number of entities} = 	ext{moles} 	imes 6.022 	imes 10$$^{23}$$

Question 17

Which of the following best describes pure diamond?

Accepted Answer

An element

Question 18

Which of the following is a correct equation for the formation of an $$\mathrm{Al}^{3+}$$ ion from a neutral aluminum atom?

Accepted Answer

$$\mathrm{Al} \rightarrow \mathrm{Al}^{3+} + 3e^-$$

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