Q: A sample contains 2.0 moles of sodium atoms. How many sodium atoms are present in the sample? (Avogadro's number $$= 6.022 \times 10$$^{23}$$\ \mathrm{mol}^{-1})$$

$$1.20 \times 10$$^{24}$$ atoms

Q: The wavelength ($$\lambda) $$and frequency ($$\nu) of $$electromagnetic radiation are related by the equation $$c = \lambda \nu. If $$the speed of light $$c = 3.00 \times 10^8$\ \mathrm{m/s}$$ and the frequency of a wave is $$6.00 \times 10$$^{14}$$\ \mathrm{Hz}$$, what is its wavelength?

$$5.00 \times 10$$^{-7}$$\ \mathrm{m}$$

Q: A photon has a wavelength of $$4.00 \times 10$$^{-7}$$\ \mathrm{m}. $$What is the energy of this photon? (Planck's constant $$h = 6.626 \times 10$$^{-34}$$\ \mathrm{J \cdot s}$$, speed of light $$c = 3.00 \times 10^8$\ \mathrm{m/s})$$

$$4.97 \times 10$$^{-19}$$\ \mathrm{J}$$

Q: A hydrogen atom's electron transitions from $$n=4 to$$ $$n=2. $$Using the equation $$E = -2.18 \times 10$$^{-18}$$\ \mathrm{J} \left( \frac{1}{n_f^2$} - \frac{1}{n_i^2$} \right)$$, what is the energy of the photon emitted?

$$4.09 \times 10$$^{-19}$$\ \mathrm{J}$$

Question 1

Which of the following correctly expresses 0.0004560 in scientific notation with the correct number of significant figures?

Accepted Answer

$$4.560 	imes 10$$^{-4}$$

Question 2

A student measures the mass of a metal cylinder as 13.42 g and its volume as 2.1 mL. What is the density of the cylinder, reported with the correct number of significant figures?

Accepted Answer

$$6.4\ \mathrm{g/mL}$$

Question 3

Convert 25.0 $$^{\circ}C to $$Kelvin.

Accepted Answer

$$298.15\ \mathrm{K}$$

Question 4

Which of the following statements best describes the Law of Conservation of Mass?

Accepted Answer

Mass is neither created nor destroyed in a chemical reaction.

Question 5

A sample contains 2.0 moles of sodium atoms. How many sodium atoms are present in the sample? (Avogadro's number $$= 6.022 	imes 10$$^{23}$$\ \mathrm{mol}^{-1})$$

Accepted Answer

$$1.20 	imes 10$$^{24}$$ atoms

Question 6

Which of the following is a heterogeneous mixture?

Accepted Answer

Salad dressing with oil and vinegar

Question 7

An atom has 17 protons, 18 neutrons, and 18 electrons. Which of the following correctly describes this species?

Accepted Answer

It is a chloride ion, $$^{35}\mathrm{Cl}^-.$$

Question 8

Which of the following statements about isotopes is correct?

Accepted Answer

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

Question 9

A certain element has two naturally occurring isotopes: $$^{10}\mathrm{B} ($$atomic mass = 10.01 u, abundance = 19.9%) and $$^{11}\mathrm{B} ($$atomic mass = 11.01 u, abundance = 80.1%). What is the average atomic mass of boron?

Accepted Answer

$$10.81\ \mathrm{u}$$

Question 10

Which of the following electromagnetic waves has the highest energy?

Accepted Answer

X-rays

Question 11

The wavelength ($$\lambda) $$and frequency ($$
u) of $$electromagnetic radiation are related by the equation $$c = \lambda 
u. If $$the speed of light $$c = 3.00 	imes 10^8$\ \mathrm{m/s}$$ and the frequency of a wave is $$6.00 	imes 10$$^{14}$$\ \mathrm{Hz}$$, what is its wavelength?

Accepted Answer

$$5.00 	imes 10$$^{-7}$$\ \mathrm{m}$$

Question 12

Which quantum number determines the shape of an atomic orbital?

Accepted Answer

The angular momentum quantum number $$l$$

Question 13

A photon has a wavelength of $$4.00 	imes 10$$^{-7}$$\ \mathrm{m}. $$What is the energy of this photon? (Planck's constant $$h = 6.626 	imes 10$$^{-34}$$\ \mathrm{J \cdot s}$$, speed of light $$c = 3.00 	imes 10^8$\ \mathrm{m/s})$$

Accepted Answer

$$4.97 	imes 10$$^{-19}$$\ \mathrm{J}$$

Question 14

Which statement best describes the significance of the DeBroglie equation in atomic theory?

Accepted Answer

It showed that particles such as electrons have wave-like properties.

Question 15

A hydrogen atom's electron transitions from $$n=4 to$$ $$n=2. $$Using the equation $$E = -2.18 	imes 10$$^{-18}$$\ \mathrm{J} \left( \frac{1}{n_f^2$} - \frac{1}{n_i^2$} ight)$$, what is the energy of the photon emitted?

Accepted Answer

$$4.09 	imes 10$$^{-19}$$\ \mathrm{J}$$

Question 16

Which of the following best describes a cation?

Accepted Answer

An ion with more protons than electrons

Question 17

Which metric prefix corresponds to $$10^{-6}$$?

Accepted Answer

Micro ($$\mu)$$

Question 18

A patient’s body temperature is measured as 102.2 $$^{\circ}F. $$What is this temperature in Celsius? (Use $$^{\circ}\mathrm{C} = \frac{5}{9}$$(^{\circ}$$\mathrm{F} - 32))$$

Accepted Answer

$$39.0\ ^{\circ}\mathrm{C}$$

Question 19

Which of the following best explains the importance of Heisenberg’s uncertainty principle in the quantum mechanical model of the atom?

Accepted Answer

It shows that it is impossible to know both the exact position and momentum of an electron simultaneously.

General Chemistry I: Exam 1 Study Guide (Chapters E, 1, 2, Appendix I)

Guida di studio - Domande di pratica

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