Q: How many atoms are in $$2.00$$ moles of carbon?

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

Question 1

Which of the following statements about significant figures is CORRECT?

Accepted Answer

Trailing zeros in a number with a decimal point are significant.

Question 2

A student adds $$12.345$$ and $$0.0028 on $$their calculator and gets $$12.3478. $$According to significant figure rules for addition, what is the correct answer?

Accepted Answer

$$12.348$$

Question 3

Which SI prefix corresponds to $$10^{-9}$$?

Accepted Answer

nano (n)

Question 4

A compound contains $$75.77\%$$ $$^{35}Cl ($$atomic mass $$= 34.96885$$ amu) and $$24.23\%$$ $$^{37}Cl ($$atomic mass $$= 36.96950$$ amu). What is the average atomic mass of chlorine?

Accepted Answer

$$35.45$$ amu

Question 5

Which of the following best describes the difference between isotopes and ions?

Accepted Answer

Isotopes have different numbers of neutrons; ions have different numbers of electrons.

Question 6

How many atoms are in $$2.00$$ moles of carbon?

Accepted Answer

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

Question 7

Which equation correctly relates the energy of a photon to its frequency?

Accepted Answer

$$E = h
u$$

Question 8

A photon has a wavelength of $$500 nm. $$Which region of the electromagnetic spectrum does it belong to?

Accepted Answer

Visible

Question 9

Which of the following is TRUE about the photoelectric effect?

Accepted Answer

Electrons are emitted only if the light's frequency is above a certain threshold.

Question 10

What is the correct set of quantum numbers for the last electron added to a phosphorus atom ($$Z=15$$)?

Accepted Answer

$$n=3,\ l=1,\ m_l=1,\ m_s=+\dfrac{1}{2}$$

Question 11

Which electron configuration represents the ground state of chromium (Cr, $$Z=24$$)?

Accepted Answer

$$[Ar]\ 4s^1$\ 3d^5$

Question 12

Which principle states that no two electrons in an atom can have the same set of four quantum numbers?

Accepted Answer

Pauli Exclusion Principle

Question 13

A sample contains $$0.500$$ mol of NaCl. How many formula units are present?

Accepted Answer

$$3.01 	imes 10$$^{23}$$

Question 14

Which of the following is a chemical property?

Accepted Answer

Reactivity with oxygen

Question 15

Which of the following best describes a heterogeneous mixture?

Accepted Answer

A mixture with visibly different components or phases

Question 16

What is the wavelength ($$\lambda) of $$light with a frequency ($$
u) of$$ $$6.00 	imes 10$$^{14}$$ Hz? (Speed of light c = 3.00$$ 	imes $$10^8 m/s)$$

Accepted Answer

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

Question 17

Which of the following is the correct noble gas notation for the electron configuration of bromine ($$Z=35$$)?

Accepted Answer

$$[Ar]\ 4s^2$\ 3d$$^{10}$$\ 4p^5$

Question 18

A baseball (mass $$= 0.145 kg) is $$thrown at $$40.0 m/s. $$What is its de Broglie wavelength? ($$h = 6.626 	imes 10$$^{-34}$$ J·s)

Accepted Answer

$$1.14 	imes 10$$^{-35}$$ m

Question 19

Which of the following best describes Hund’s Rule?

Accepted Answer

Electrons fill degenerate orbitals singly before pairing.

CH 221z Midterm 1 Review: General Chemistry Study Guide

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