Q: How many atoms are present in 44.7 g of Zn (atomic mass = 65.38 g/mol)?

$$4.11 \times 10$$^{23}$$ atoms

Q: A sample of $$111.1 g of Li ($$atomic mass $$= 6.941 g/$$mol) contains how many atoms?

$$9.63 \times 10$$^{24}$$ atoms

Question 1

Which of the following best describes a homogeneous mixture?

Accepted Answer

A mixture in which the composition is uniform throughout, such as air or salt water.

Question 2

How many atoms are present in 44.7 g of Zn (atomic mass = 65.38 g/mol)?

Accepted Answer

$$4.11 	imes 10$$^{23}$$ atoms

Question 3

Which statement about the law of conservation of mass is correct?

Accepted Answer

The total mass of reactants equals the total mass of products in a chemical reaction.

Question 4

A radio wave has a wavelength of $$3.5 	imes 10^6$ m. What is the frequency of this wave? (Speed of light c = 3.00$$ 	imes $$10^8 m/s)$$

Accepted Answer

$$8.6 	imes 10^1$ Hz

Question 5

Which of the following is a chemical change?

Accepted Answer

Burning wood in a fireplace

Question 6

Given the reaction: $$\mathrm{CH_4$(g) + 2\ O_2$(g) \rightarrow CO_2$(g) + 2\ H_2O(g)}$$, how many molecules of $$\mathrm{O_2$}$$ are required to completely react with 3 molecules of $$\mathrm{CH_4$}$$?

Accepted Answer

6 molecules

Question 7

Which isotope of carbon is most abundant based on the provided data?

Accepted Answer

$$^{12}\mathrm{C}$$

Question 8

Which color of visible light has the highest energy?

Accepted Answer

Violet

Question 9

What is the energy of a photon with a frequency of $$5.17 	imes 10$$^{21}$$ Hz? (Planck's constant h = 6.626$$ 	imes $$10^{-34} J$$·s)

Accepted Answer

$$3.43 	imes 10$$^{-12}$$ J

Question 10

Which of the following best explains why the mass spectrum of boron shows two peaks?

Accepted Answer

Boron has two naturally occurring isotopes with different masses.

Question 11

A sample contains $$5.67 	imes 10$$^{24}$$ atoms of Mg. What is the mass of this sample? (Atomic mass of Mg = 24.31 g/mol, 1$ mol = 6.022$$ 	imes $$10^{23}$$ atoms)

Accepted Answer

229 g

Question 12

Which of the following statements about compounds and mixtures is correct?

Accepted Answer

Compounds can only be separated into their elements by chemical reactions.

Question 13

Which equation correctly relates the speed of light ($$c$$), wavelength ($$\lambda$$), and frequency ($$
u$$)?

Accepted Answer

$$c = \lambda 
u$$

Question 14

If an atom has 34 neutrons and 29 protons, what is its atomic number and how many electrons does it have in a neutral atom?

Accepted Answer

Atomic number 29, 29 electrons

Question 15

Which of the following best describes the difference between amplitude and frequency in a wave?

Accepted Answer

Amplitude is the height of the wave, frequency is the number of cycles per second.

Question 16

An electron in a hydrogen atom transitions from $$n=3 to$$ $$n=2. $$Which statement is true about the energy change?

Accepted Answer

Energy is released as a photon when the electron moves from $$n=3 to$$ $$n=2.$$

Question 17

Which of the following is a correct statement about physical and chemical changes?

Accepted Answer

Physical changes involve rearrangement of matter without changing chemical identity.

Question 18

What is the frequency of light with a wavelength of $$579 nm$$? (Speed of light $$c = 3.00 	imes 10^8$ m/s)

Accepted Answer

$$5.18 	imes 10$$^{14}$$ Hz

Question 19

Which of the following best explains why red light has less energy than blue light?

Accepted Answer

Red light has a longer wavelength and lower frequency than blue light.

Question 20

A sample of $$111.1 g of Li ($$atomic mass $$= 6.941 g/$$mol) contains how many atoms?

Accepted Answer

$$9.63 	imes 10$$^{24}$$ atoms

General Chemistry Fundamentals: Atomic Structure, Mole Calculations, and Quantum Theory

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