Q: A sample contains $$2.0\ mol of$$ $$H_2O. $$How many molecules are present? ($$1\ mol = 6.022 \times 10$$^{23}$$ molecules)

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

Question 1

Which of the following correctly applies the rules for significant figures when adding $$12.34$$, $$0.56$$, and $$7.1$$?

Accepted Answer

$$12.34 + 0.56 + 7.1 = 20.0$$

Question 2

Convert $$3.25 	imes 10^4$ to standard notation.

Accepted Answer

$$32,500$$

Question 3

Which of the following is a physical change?

Accepted Answer

Boiling water to produce steam

Question 4

A patient’s temperature is $$39.0\ ^\circ C. $$What is this temperature in Fahrenheit? Use $$F = \frac{9}{5}C + 32.$$

Accepted Answer

$$102.2\ ^\circ F$$

Question 5

Which of the following is a homogeneous mixture?

Accepted Answer

Salt dissolved in water

Question 6

Which of the following is a compound?

Accepted Answer

Carbon dioxide ($$CO_2)$$

Question 7

Which of the following is an intensive property?

Accepted Answer

Density

Question 8

A sample of gold has a mass of $$96.5\ g$$ and a volume of $$5.00\ cm^3$. What is its density?

Accepted Answer

$$19.3\ g/cm^3$

Question 9

Which of the following best describes an element?

Accepted Answer

A substance that cannot be broken down into simpler substances by chemical means

Question 10

Which of the following is the correct scientific notation for $$0.00045$$?

Accepted Answer

$$4.5 	imes 10$$^{-4}$$

Question 11

A solution is prepared by dissolving $$5.0\ g of $$NaCl in $$95.0\ g of $$water. What is the percent by mass of NaCl in the solution?

Accepted Answer

$$5.0\%$$

Question 12

Which of the following is an example of a chemical property?

Accepted Answer

Iron reacts with oxygen to form rust

Question 13

Which of the following is the correct conversion for $$250\ K to$$ $$^\circ C$$? Use $$C = K - 273.15.$$

Accepted Answer

$$-23.15\ ^\circ C$$

Question 14

Which of the following best describes a heterogeneous mixture?

Accepted Answer

A mixture in which the composition is not uniform throughout

Question 15

A student measures the mass of a sample three times and gets $$2.01\ g$$, $$2.00\ g$$, and $$2.02\ g. $$The true mass is $$2.50\ g. $$Which statement is correct?

Accepted Answer

The measurements are precise but not accurate.

Question 16

Which of the following is the correct way to round $$3.4567 to $$three significant figures?

Accepted Answer

$$3.46$$

Question 17

A chemical reaction releases $$150\ kJ of $$energy. What is this energy in calories? ($$1\ cal = 4.184\ J)$$

Accepted Answer

$$3.6 	imes 10^4$\ cal$$

Question 18

Which of the following is an example of an extensive property?

Accepted Answer

Volume

Question 19

Which of the following best describes a pure substance?

Accepted Answer

A material with a fixed composition and distinct properties

Question 20

A sample contains $$2.0\ mol of$$ $$H_2O. $$How many molecules are present? ($$1\ mol = 6.022 	imes 10$$^{23}$$ molecules)

Accepted Answer

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

Exam 1 Study Guide: CHM 130 (Chapters 1-3) – Chemistry in Our Lives, Measurements, Matter & Energy

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