Question 1

Which of the following statements best describes the difference between a compound and a mixture?

Accepted Answer

A compound consists of two or more elements chemically bonded in fixed proportions, while a mixture contains two or more substances physically combined in variable proportions.

Question 2

Which of the following prefixes represents the largest multiplier?

Accepted Answer

mega ($$10^6)$$

Question 3

A sample contains $$2.5 	imes 10$$^{24}$$ molecules of water. How many moles of water are present in the sample? (N_A = 6.022$$ 	imes $$10^{23}$$ mol$$^{-1})$$

Accepted Answer

$$4.15$$ moles

Question 4

Which of the following best explains why atomic radius decreases across a period in the periodic table?

Accepted Answer

The effective nuclear charge increases, pulling electrons closer to the nucleus.

Question 5

Which of the following elements has the highest electronegativity?

Accepted Answer

Fluorine

Question 6

Which quantum number determines the shape of an orbital?

Accepted Answer

Angular momentum quantum number ($$l)$$

Question 7

What is the energy change ($$\Delta E) $$when an electron in a hydrogen atom transitions from $$n=3 to$$ $$n=2$$? Use $$R_H = 2.17987 	imes 10$$^{-18}$$ J.

Accepted Answer

$$\Delta E = -R_H \left( \dfrac{1}{2^2$} - \dfrac{1}{3^2$} \right)$$

Question 8

Which statement about the duality of matter is correct?

Accepted Answer

All matter exhibits both wave and particle properties.

Question 9

Which of the following best describes the Pauli Exclusion Principle?

Accepted Answer

No two electrons in an atom can have the same set of four quantum numbers.

Question 10

Which of the following ions has the same electron configuration as neon ($$1s^2$$ $$2s^2$$ $$2p^6$$)?

Accepted Answer

$$	ext{Na}^+$$

Question 11

Which of the following is the correct formula for the de Broglie wavelength?

Accepted Answer

$$\lambda = \dfrac{h}{mv}$$

Question 12

Which of the following best explains why successive ionization energies increase for an atom?

Accepted Answer

Each electron removed experiences a stronger effective nuclear charge.

Question 13

Which of the following statements about effective nuclear charge ($$Z_{eff}) is $$correct?

Accepted Answer

$$Z_{eff}$$ increases left to right across a period.

Question 14

Which of the following elements is most likely to have metallic character?

Accepted Answer

Sodium

Question 15

Which of the following is the correct relationship between frequency ($$
u) $$and wavelength ($$\lambda) of $$electromagnetic radiation?

Accepted Answer

$$c = \lambda 
u$$

Question 16

Which of the following best describes Hund's Rule?

Accepted Answer

Electrons fill degenerate orbitals singly before pairing.

Question 17

Which of the following is the correct electron configuration for a neutral oxygen atom?

Accepted Answer

$$1s^2$$ $$2s^2$$ $$2p^4$$

Question 18

Which of the following best explains why the first ionization energy of sodium is lower than that of magnesium?

Accepted Answer

Sodium has a lower effective nuclear charge than magnesium.

Question 19

Which of the following statements about electron affinity is correct?

Accepted Answer

Electron affinity generally becomes more negative from left to right across a period.

Question 20

Which of the following is the correct formula for calculating the density of a substance?

Accepted Answer

$$	ext{Density} = \dfrac{	ext{mass}}{	ext{volume}}$$

General Chemistry I: Comprehensive Study Guide

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