Q: If 84.2 g of pitchblende contains 71.4 g of uranium, how many grams of uranium can be obtained from 102 kg of pitchblende?

$$102 \times \frac{71.4}{84.2} \times 1000 = 8.65 \times 10^4$ g

Q: Calculate the atomic mass of silver given the following data: $$^{107}Ag (106.90509 $$amu, 51.84%), $$^{109}Ag (108.90476 $$amu, 48.16%).

$$106.90509 \times 0.5184 + 108.90476 \times 0.4816 = 107.87$$ amu

Q: What is the molecular mass of ammonium nitrate ($$NH_4NO_3$$)? (Atomic masses: N = 14.01 amu, H = 1.008 amu, O = 16.00 amu)

$$(2 \times 14.01) + (4 \times 1.008) + (3 \times 16.00) = 80.05$$ amu

Question 1

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

Accepted Answer

An element consists of only one type of atom, while a compound consists of two or more elements chemically combined.

Question 2

According to Dalton’s Atomic Theory, which statement is correct regarding chemical reactions?

Accepted Answer

Atoms are rearranged during a chemical reaction, but are not created or destroyed.

Question 3

A sample of calcium carbonate contains 8.0 g calcium, 2.4 g carbon, and 9.6 g oxygen. What is the mass fraction of oxygen in this sample?

Accepted Answer

$$\frac{9.6}{20.0} = 0.48$$

Question 4

Which law states that the total mass of substances does not change during a chemical reaction?

Accepted Answer

Law of Mass Conservation

Question 5

If 84.2 g of pitchblende contains 71.4 g of uranium, how many grams of uranium can be obtained from 102 kg of pitchblende?

Accepted Answer

$$102 	imes \frac{71.4}{84.2} 	imes 1000 = 8.65 	imes 10^4$ g

Question 6

Which law is illustrated when two compounds formed from the same elements have mass ratios of those elements that can be expressed as small whole numbers?

Accepted Answer

Law of Multiple Proportions

Question 7

Which experiment led to the discovery of the atomic nucleus?

Accepted Answer

Rutherford’s alpha-scattering experiment

Question 8

What is the charge and location of a neutron in an atom?

Accepted Answer

0 charge, located in the nucleus

Question 9

How many protons, neutrons, and electrons are in $$^{29}Si$$?

Accepted Answer

14 protons, 15 neutrons, 14 electrons

Question 10

Calculate the atomic mass of silver given the following data: $$^{107}Ag (106.90509 $$amu, 51.84%), $$^{109}Ag (108.90476 $$amu, 48.16%).

Accepted Answer

$$106.90509 	imes 0.5184 + 108.90476 	imes 0.4816 = 107.87$$ amu

Question 11

Which group in the periodic table contains elements that are so stable they hardly ever react to form compounds?

Accepted Answer

Noble gases

Question 12

Which of the following is a property of metals?

Accepted Answer

Good conductor of electricity and malleable

Question 13

What is the empirical formula for magnesium nitride?

Accepted Answer

$$Mg_3N_2$$

Question 14

Which of the following ions is formed when aluminum (Z = 13) achieves the same number of electrons as neon?

Accepted Answer

$$Al^{3+}$$

Question 15

What is the correct name for the compound $$Fe($$ClO_4$$)_2$$?

Accepted Answer

Iron(II) perchlorate

Question 16

Which separation technique is based on differences in volatility?

Accepted Answer

Distillation

Question 17

What is the molecular mass of ammonium nitrate ($$NH_4NO_3$$)? (Atomic masses: N = 14.01 amu, H = 1.008 amu, O = 16.00 amu)

Accepted Answer

$$(2 	imes 14.01) + (4 	imes 1.008) + (3 	imes 16.00) = 80.05$$ amu

Question 18

Which of the following best describes a homogeneous mixture?

Accepted Answer

A mixture with no visible boundaries between components, mixed as individual atoms, ions, and molecules.

Question 19

Which acid is formed when the anion sulfate ($$SO_4$$^{2-}$$) is dissolved in water?

Accepted Answer

Sulfuric acid ($$H_2SO_4)$$

Chapter 2: The Components of Matter – Atomic Theory, Elements, Compounds, and Mixtures

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