Q: How many atoms are present in 2 molecules of $$\mathrm{H_2SO_4}$$?

$$2 \times (2 + 1 + 4) = 14$$ atoms

Q: Given the formula $$\mathrm{Ca_3$(PO_4$)_2}$$, how many oxygen atoms are present in 3 molecules?

$$3 \times 8 = 24$$ oxygen atoms

Q: If you have 5 molecules of $$\mathrm{$$CaSO_4$$ \cdot 5H_2O}$$, how many hydrogen atoms are present?

$$5 \times 2 \times 5 = 50$$ hydrogen atoms

Q: How many atoms are present in 2 molecules of $$\mathrm{C_6H_{12}O_6$}$$?

$$2 \times (6 + 12 + 6) = 48$$ atoms

Q: What is the total number of atoms in 3 molecules of $$\mathrm{Ca_3$(PO_4$)_2}$$?

$$3 \times (3 + 2 \times (1 + 4)) = 3 \times (3 + 2 \times 5) = 3 \times (3 + 10) = 3 \times 13 = 39$$ atoms

Question 1

Which of the following best describes a molecule of $$\mathrm{H_2SO_4}$$?

Accepted Answer

A group of atoms bonded together representing the smallest unit of a compound.

Question 2

How many atoms are present in 2 molecules of $$\mathrm{H_2SO_4}$$?

Accepted Answer

$$2 	imes (2 + 1 + 4) = 14$$ atoms

Question 3

Which statement correctly distinguishes a pure substance from a mixture?

Accepted Answer

A pure substance has a fixed composition and constant properties, while a mixture has variable composition and properties.

Question 4

Given the formula $$\mathrm{Ca_3$(PO_4$)_2}$$, how many oxygen atoms are present in 3 molecules?

Accepted Answer

$$3 	imes 8 = 24$$ oxygen atoms

Question 5

Which of the following is an example of a simple pure substance?

Accepted Answer

$$\mathrm{O_2$}$$

Question 6

What is the atomicity of $$\mathrm{C_6H_{12}O_6$}$$?

Accepted Answer

$$6 + 12 + 6 = 24$$

Question 7

Which property is NOT characteristic of a mixture?

Accepted Answer

Fixed composition

Question 8

If you have 5 molecules of $$\mathrm{$$CaSO_4$$ \cdot 5H_2O}$$, how many hydrogen atoms are present?

Accepted Answer

$$5 	imes 2 	imes 5 = 50$$ hydrogen atoms

Question 9

Which of the following best describes a metallic bond?

Accepted Answer

A bond formed by the sharing of free electrons among a lattice of metal atoms.

Question 10

Which scenario represents a eutectic mixture?

Accepted Answer

A mixture of two substances that melts at a lower temperature than either of the pure substances.

Question 11

How many atoms are present in 2 molecules of $$\mathrm{C_6H_{12}O_6$}$$?

Accepted Answer

$$2 	imes (6 + 12 + 6) = 48$$ atoms

Question 12

Which of the following is NOT a pure substance?

Accepted Answer

Air

Question 13

What is the total number of atoms in 3 molecules of $$\mathrm{Ca_3$(PO_4$)_2}$$?

Accepted Answer

$$3 	imes (3 + 2 	imes (1 + 4)) = 3 	imes (3 + 2 	imes 5) = 3 	imes (3 + 10) = 3 	imes 13 = 39$$ atoms

Question 14

Which of the following is a characteristic of a pure substance?

Accepted Answer

It has a constant melting and boiling point.

Question 15

Which of the following is an example of a mixture?

Accepted Answer

Air

Question 16

If you have 4 molecules of $$\mathrm{Na_2SO_4}$$, how many sodium atoms are present?

Accepted Answer

$$4 	imes 2 = 8$$ sodium atoms

Question 17

Which of the following is NOT a property of a pure substance?

Accepted Answer

Variable composition

Question 18

Which of the following is a compound?

Accepted Answer

$$\mathrm{H_2O}$$

Question 19

What is the total number of atoms in 2 molecules of $$\mathrm{Na_2SO_4}$$?

Accepted Answer

$$2 	imes (2 + 1 + 4) = 14$$ atoms

Atoms, Molecules, and Classification of Substances

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