Q: Which of the following is the correct formula for calculating the number of molecules in a given number of moles?

$$\text{Number of molecules} = \text{moles} \times 6.022 \times 10$$^{23}$$

Q: If you have $$12$$ grams of carbon ($$\mathrm{C}$$), how many atoms of carbon do you have? (Molar mass of C = $$12 g/$$mol, Avogadro's number = $$6.022 \times 10$$^{23}$$)

$$6.022 \times 10$$^{23}$$ atoms

Q: If you have $$0.5$$ moles of $$\mathrm{O_2$}$$, how many molecules of $$\mathrm{O_2$} do $$you have? (Avogadro's number = $$6.022 \times 10$$^{23}$$)

$$3.011 \times 10$$^{23}$$ molecules

Q: Which of the following is the correct formula for calculating the mass of an element in a compound, given the moles of the compound?

$$\text{Mass of element} = \text{moles of compound} \times \text{number of atoms of element per formula unit} \times \text{atomic mass of element}$$

Question 1

Which of the following best describes a diatomic element?

Accepted Answer

An element that exists naturally as molecules composed of two atoms, such as $$\mathrm{O_2$} or$$ $$\mathrm{N_2$}.$$

Question 2

Which of the following is an example of an ionic compound?

Accepted Answer

$$\mathrm{NaCl}$$

Question 3

Given the periodic table, which group contains the alkali metals?

Accepted Answer

Group 1 (first column on the left, excluding hydrogen)

Question 4

Which of the following best describes the location of transition metals on the periodic table?

Accepted Answer

They are found in the center block, spanning groups 3 to 12.

Question 5

What is the formula mass (in amu) of $$\mathrm{H_2O}$$? (Atomic masses: H = 1.0 amu, O = 16.0 amu)

Accepted Answer

$$18.0$$ amu

Question 6

A sample contains $$36$$ grams of water ($$\mathrm{H_2O}). $$How many moles of water are present? (Molar mass of $$\mathrm{H_2O}$$ = $$18 g/$$mol)

Accepted Answer

$$2$$ moles

Question 7

Which of the following is the correct formula for calculating the number of molecules in a given number of moles?

Accepted Answer

$$	ext{Number of molecules} = 	ext{moles} 	imes 6.022 	imes 10$$^{23}$$

Question 8

If you have $$12$$ grams of carbon ($$\mathrm{C}$$), how many atoms of carbon do you have? (Molar mass of C = $$12 g/$$mol, Avogadro's number = $$6.022 	imes 10$$^{23}$$)

Accepted Answer

$$6.022 	imes 10$$^{23}$$ atoms

Question 9

Which of the following best describes a molecular compound?

Accepted Answer

A compound formed by the sharing of electrons between nonmetal atoms.

Question 10

What is the charge on the iron ion in $$\mathrm{$$FeCl_3$$}$$?

Accepted Answer

$$+3$$

Question 11

How many grams of sodium are in $$58.5$$ grams of $$\mathrm{NaCl}$$? (Molar mass: Na = $$23 g/$$mol, Cl = $$35.5 g/$$mol)

Accepted Answer

$$23$$ grams

Question 12

Which of the following is the correct molar mass of $$\mathrm{CO_2$}$$? (Atomic masses: C = $$12 g/$$mol, O = $$16 g/$$mol)

Accepted Answer

$$44 g/$$mol

Question 13

A compound contains $$2$$ moles of hydrogen and $$1$$ mole of oxygen. What is its empirical formula?

Accepted Answer

$$\mathrm{H_2O}$$

Question 14

Which of the following is a noble gas?

Accepted Answer

Neon ($$\mathrm{Ne})$$

Question 15

If you have $$0.5$$ moles of $$\mathrm{O_2$}$$, how many molecules of $$\mathrm{O_2$} do $$you have? (Avogadro's number = $$6.022 	imes 10$$^{23}$$)

Accepted Answer

$$3.011 	imes 10$$^{23}$$ molecules

Question 16

Which of the following best describes the mascot of the American Chemical Society (the Mole)?

Accepted Answer

A small, burrowing mammal used as a pun for the unit 'mole' in chemistry.

Question 17

A student needs to prepare $$100$$ grams of $$\mathrm{NaOH}$$ solution. How many moles of $$\mathrm{NaOH}$$ are in $$100$$ grams? (Molar mass of $$\mathrm{NaOH}$$ = $$40 g/$$mol)

Accepted Answer

$$2.5$$ moles

Question 18

Which of the following is the correct formula for calculating the mass of an element in a compound, given the moles of the compound?

Accepted Answer

$$	ext{Mass of element} = 	ext{moles of compound} 	imes 	ext{number of atoms of element per formula unit} 	imes 	ext{atomic mass of element}$$

Question 19

Which of the following is the correct name for $$\mathrm{H_2SO_4}$$?

Accepted Answer

Sulfuric acid

Question 20

A patient is given $$0.9$$ grams of sodium chloride ($$\mathrm{NaCl}) in a $$saline IV. How many moles of $$\mathrm{NaCl} is $$this? (Molar mass of $$\mathrm{NaCl}$$ = $$58.5 g/$$mol)

Accepted Answer

$$0.015$$ moles

Introduction to Chemistry: Atomic Structure, Periodic Table, and Moles

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