Q: A sample contains $$0.158 g of $$phosphorus. How many phosphorus atoms are present? (Atomic mass of P = $$30.97 g/$$mol, Avogadro's number $$= 6.022 \times 10$$^{23}$$)

$$3.08 \times 10$$^{21}$$ atoms

Question 1

A sample of chlorine gas contains two naturally occurring isotopes: Cl-35 (mass = 34.969 amu, abundance = 75.78%) and Cl-37 (mass = 36.966 amu, abundance = 24.22%). What is the atomic mass of chlorine?

Accepted Answer

$$35.45$$ amu

Question 2

Which of the following statements best describes a chemical change?

Accepted Answer

Iron rusting in moist air

Question 3

A student measures the mass of a metal sample as $$12.48 g $$and its volume as $$8.0 mL. $$What is the density of the metal?

Accepted Answer

$$1.56 g/mL$$

Question 4

Which of the following numbers has the greatest number of significant figures?

Accepted Answer

$$0.050700$$

Question 5

A compound contains $$66.6\% C$$, $$11.2\% H$$, and $$22.2\% O by $$mass. What is its empirical formula?

Accepted Answer

$$C_2H_4O$$

Question 6

Which of the following elements is a halogen?

Accepted Answer

Cl

Question 7

A sample contains $$0.158 g of $$phosphorus. How many phosphorus atoms are present? (Atomic mass of P = $$30.97 g/$$mol, Avogadro's number $$= 6.022 	imes 10$$^{23}$$)

Accepted Answer

$$3.08 	imes 10$$^{21}$$ atoms

Question 8

Which of the following is NOT an empirical formula?

Accepted Answer

$$C_2H_4O$$

Question 9

A medication is prescribed at $$6.00 mg/kg $$for a patient weighing $$166 lb. (1 lb$$ = $$453.59 g). $$What is the recommended dose in mg?

Accepted Answer

$$452 mg$$

Question 10

Which of the following best describes an ionic bond?

Accepted Answer

The transfer of electrons from one atom to another

Question 11

How many kilograms of carbon are present in $$10.0$$ moles of C atoms? (Atomic mass of C = $$12.01 g/$$mol)

Accepted Answer

$$0.120 kg$$

Question 12

Which of the following is a molecular compound?

Accepted Answer

$$CO_2$$

Question 13

What is the mass percent of hydrogen in sodium bicarbonate ($$NaHCO_3$$)? (Molar mass $$= 84.01 g/$$mol)

Accepted Answer

$$1.20\%$$

Question 14

Which of the following is an example of a homogeneous mixture?

Accepted Answer

Air in a room

Question 15

A student performs a calculation: $$4.553 	imes 3.9119 + 9431.4316. $$What answer should be reported, using the correct number of significant figures?

Accepted Answer

$$1.13 	imes 10^4$

Question 16

Which of the following statements about subatomic particles is FALSE?

Accepted Answer

Protons have about the same mass as electrons.

Question 17

Which symbol is used to represent the SI prefix factor of $$10^3$$?

Accepted Answer

k

Question 18

Which of the following is the correct formula for strontium perchlorate?

Accepted Answer

$$Sr($$ClO_4$$)_2$$

Question 19

A sample contains $$9.44 	imes 10$$^{21}$$ molecules of NO_2$. The molar mass of NO_2$ is 46.01$ g/mol. What is the mass of NO_2$ in the sample?

Accepted Answer

$$0.721 g$$

Question 20

Which of the following best defines potential energy?

Accepted Answer

Energy associated with the position or composition of an object

General Chemistry Exam Study Guide: Atoms, Elements, Molecules, and Compounds

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