Q: A photon has a wavelength of $$4.00 \times 10$$^{-7}$$\ \mathrm{m}. $$What is its energy? (Use $$c = 2.998 \times 10^8$\ \mathrm{m/s}$$ and $$h = 6.63 \times 10$$^{-34}$$\ \mathrm{J\cdot s})$$

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

Question 1

Which of the following best describes the difference between precision and accuracy in a set of measurements?

Accepted Answer

Precision refers to how close measurements are to each other, while accuracy refers to how close measurements are to the true value.

Question 2

A sample of a metal has a mass of $$15.0\ \mathrm{g}$$ and a volume of $$3.0\ \mathrm{cm}^3. $$What is its density?

Accepted Answer

$$5.0\ \mathrm{g/cm}^3$$

Question 3

Which of the following is an example of an intensive property?

Accepted Answer

Density

Question 4

Which statement best explains why the Rutherford gold foil experiment led to the replacement of the plum pudding model of the atom?

Accepted Answer

Some alpha particles were deflected at large angles, indicating a small, dense, positively charged nucleus.

Question 5

A neutral atom of $$^{37}\mathrm{Cl}$$ has an atomic number of $$17. $$How many protons, neutrons, and electrons does it contain?

Accepted Answer

17 protons, 20 neutrons, 17 electrons

Question 6

Which of the following best describes the law of definite proportions?

Accepted Answer

A chemical compound always contains exactly the same proportion of elements by mass.

Question 7

A sample contains $$0.250\ \mathrm{mol} of$$ $$\mathrm{CO}_2. $$How many molecules of $$\mathrm{CO}_2$$ are present? (Avogadro's number $$= 6.022 	imes 10$$^{23}$$)

Accepted Answer

$$1.51 	imes 10$$^{24}$$

Question 8

Which of the following sets of quantum numbers is NOT allowed for an electron in an atom?

Accepted Answer

$$n=2,\ l=2,\ m_l=0,\ m_s=+\frac{1}{2}$$

Question 9

Which of the following best explains why sodium ($$\mathrm{Na}) $$and lithium ($$\mathrm{Li}) $$have similar chemical properties?

Accepted Answer

They have the same number of valence electrons.

Question 10

Which of the following ions is largest in size?

Accepted Answer

$$\mathrm{F}^-$$

Question 11

A photon has a wavelength of $$4.00 	imes 10$$^{-7}$$\ \mathrm{m}. $$What is its energy? (Use $$c = 2.998 	imes 10^8$\ \mathrm{m/s}$$ and $$h = 6.63 	imes 10$$^{-34}$$\ \mathrm{J\cdot s})$$

Accepted Answer

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

Question 12

Which of the following statements about the photoelectric effect is correct?

Accepted Answer

Electrons are emitted from a metal only if the light has a frequency above a certain threshold.

Question 13

Which of the following best describes an exothermic process?

Accepted Answer

A process in which the system releases heat to the surroundings.

Question 14

Which of the following is the correct electron configuration for the $$\mathrm{O}^{2-}$$ ion?

Accepted Answer

$$1s^2$$\ $$2s^2$$\ $$2p^6$$

Question 15

Which of the following statements about isotopic abundance and atomic weight is correct?

Accepted Answer

The atomic weight of an element is the average of the masses of its isotopes, weighted by their natural abundance.

Question 16

Which of the following best describes the uncertainty principle?

Accepted Answer

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

Question 17

Which of the following best explains why the atomic weight of an element is not a constant of nature?

Accepted Answer

Atomic weight depends on the relative abundance of isotopes, which can vary in different samples.

Question 18

Which of the following statements about Coulomb's Law and orbital energy ordering is correct?

Accepted Answer

Coulomb's Law explains that electrons closer to the nucleus experience a stronger attraction, resulting in lower energy orbitals.

Question 19

A student needs to convert $$2.5\ \mathrm{mg} to$$ $$\mathrm{g}. $$What is the correct value?

Accepted Answer

$$2.5 	imes 10$$^{-3}$$\ \mathrm{g}$$

Question 20

Which of the following best describes a node in an atomic orbital?

Accepted Answer

A region where the probability of finding an electron is zero.

General Chemistry Study Guide: Chapters E, 1, 2, and 3

Guida di studio - Domande di pratica

Study guide - Flashcard