Q: How many atoms are there in a helium blimp containing 526 kg of helium? (Molar mass He = 4.0 g/mol)

$$7.92 \times 10$$^{28}$$ atoms

Q: A sample of lead in blood is measured at 30 mg/dL. What is this concentration in mol Pb/L? (Molar mass Pb = 207.2 g/mol)

$$1.5 \times 10$$^{-4}$$ mol Pb/L

Question 1

Which law states that in a chemical reaction, matter is neither created nor destroyed, and the total mass of reactants equals the total mass of products?

Accepted Answer

Law of Conservation of Mass

Question 2

A 100.0 g sample of sodium chloride contains 39.3 g of sodium and 60.7 g of chlorine. If a 200.0 g sample contains 78.6 g of sodium and 121.4 g of chlorine, which law does this data support?

Accepted Answer

Law of Definite Proportions

Question 3

When two elements form more than one compound, the masses of one element that combine with a fixed mass of the other element are in ratios of small whole numbers. This is known as:

Accepted Answer

Law of Multiple Proportions

Question 4

In the reaction $$\mathrm{CH_4$} + 2\mathrm{O_2$} \rightarrow \mathrm{CO_2$} + 2\mathrm{H_2O}$$, if you start with 16 g of methane and 64 g of oxygen, what is the total mass of products formed?

Accepted Answer

$$80\ \mathrm{g}$$

Question 5

Which experiment led to the discovery of the electron and the measurement of its charge-to-mass ratio?

Accepted Answer

Cathode Ray Tube Experiment

Question 6

Which scientist is credited with the discovery of the neutron?

Accepted Answer

James Chadwick

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

$$18$$

Question 8

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

Accepted Answer

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

Question 9

A cation has 24 protons, 28 neutrons, and 21 electrons. What is the correct isotope symbol?

Accepted Answer

$$\mathrm{Cr$$^{3+}$$_{52}}$$

Question 10

Calculate the average atomic mass of neon given the following data: $$^{20}\mathrm{Ne} (90.48$$%, 19.99244 u), $$^{21}\mathrm{Ne} (0.27$$%, 20.99385 u), $$^{22}\mathrm{Ne} (9.25$$%, 21.99139 u).

Accepted Answer

$$20.18\ \mathrm{u}$$

Question 11

How many atoms are there in a helium blimp containing 526 kg of helium? (Molar mass He = 4.0 g/mol)

Accepted Answer

$$7.92 	imes 10$$^{28}$$ atoms

Question 12

Which of the following best describes an isotope?

Accepted Answer

Atoms with the same number of protons but different numbers of neutrons

Question 13

A sample of lead in blood is measured at 30 mg/dL. What is this concentration in mol Pb/L? (Molar mass Pb = 207.2 g/mol)

Accepted Answer

$$1.5 	imes 10$$^{-4}$$ mol Pb/L

Question 14

Which experiment provided evidence that the atom has a small, dense, positively charged nucleus?

Accepted Answer

Gold Foil Experiment

Question 15

Which subatomic particle has a relative charge of $$-1$$ and a mass of approximately $$9.11 	imes 10$$^{-31}$$ kg?

Accepted Answer

Electron

Question 16

If a neutral atom has 10 protons, 12 neutrons, and 10 electrons, what is its atomic number and mass number?

Accepted Answer

Atomic number = 10, Mass number = 22

Question 17

A gold foil has dimensions $$1.0\ \mathrm{cm} 	imes 1.0\ \mathrm{cm} 	imes 4.0 	imes 10$$^{-5}$$\ \mathrm{cm}$$ and a density of $$19.3\ \mathrm{g/cm^3$}. $$What is the number of moles of gold in the foil? (Molar mass Au = 197.97 g/mol)

Accepted Answer

$$4.0 	imes 10$$^{-3}$$ mol

Question 18

Which of the following is a correct statement about ions?

Accepted Answer

Cations have more protons than electrons.

Question 19

A neutral atom of an element has 34 protons and 42 neutrons. What is its isotope symbol?

Accepted Answer

$$^{76}_{34}\mathrm{Se}$$

Atoms and Elements: Laws, Atomic Theory, and Atomic Structure

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