Question 1

A sample of water is heated from $$25 ^\circ \mathrm{C} to$$ $$75 ^\circ \mathrm{C}. If $$the mass of the water is $$100 \ \mathrm{g}$$, how much energy (in joules) is required? (Specific heat of water $$= 4.184 \ \mathrm{J}/\mathrm{g}^\circ \mathrm{C})$$

Accepted Answer

$$20,920 \ \mathrm{J}$$

Question 2

Which of the following best describes a hypothesis in the scientific method?

Accepted Answer

A tentative explanation that can be tested by experiments.

Question 3

Convert a temperature of $$68 ^\circ \mathrm{F} to $$degrees Celsius using the provided formula.

Accepted Answer

$$20 ^\circ \mathrm{C}$$

Question 4

Which of the following is a physical change?

Accepted Answer

Melting of ice

Question 5

A student measures the mass of a sample as $$2.50 \ \mathrm{g}$$ and its volume as $$1.25 \ \mathrm{mL}. $$What is the density of the sample?

Accepted Answer

$$2.00 \ \mathrm{g}/\mathrm{mL}$$

Question 6

Which of the following statements about elements and compounds is correct?

Accepted Answer

A compound contains atoms of two or more different elements chemically bonded together.

Question 7

Which of the following is the correct value for Avogadro's number ($$N_A$$)?

Accepted Answer

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

Question 8

A compound has a molar mass of $$58.44 \ \mathrm{g}/\mathrm{mol}$$ and contains $$23.0 \ \mathrm{g} of $$sodium per mole. What is the percent by mass of sodium in the compound?

Accepted Answer

$$39.4\%$$

Question 9

Which of the following is a chemical property?

Accepted Answer

Ability of iron to rust

Question 10

A student needs to convert $$5.00$$ miles to kilometers. Using the conversion factor $$1 \ \mathrm{mi} = 1.609 \ \mathrm{km}$$, what is the correct answer?

Accepted Answer

$$8.05 \ \mathrm{km}$$

Question 11

Which of the following best describes a heterogeneous mixture?

Accepted Answer

A mixture in which the composition is not uniform throughout.

Question 12

Which of the following is the correct formula for calculating the molecular weight ($$MW) of a $$compound?

Accepted Answer

$$MW = \dfrac{\mathrm{grams}}{\mathrm{mole}}$$

Question 13

A student dissolves $$10.0 \ \mathrm{g} of $$NaCl in enough water to make $$250 \ \mathrm{mL} of $$solution. What is the concentration in $$\mathrm{g}/\mathrm{mL}$$?

Accepted Answer

$$0.040 \ \mathrm{g}/\mathrm{mL}$$

Question 14

Which of the following is NOT a base SI unit?

Accepted Answer

Liter

Question 15

Which of the following is a correct statement about the law of conservation of mass?

Accepted Answer

The total mass of reactants equals the total mass of products in a chemical reaction.

Question 16

A student needs to convert $$250 \ \mathrm{cal} to $$joules. Using the conversion $$1 \ \mathrm{cal} = 4.184 \ \mathrm{J}$$, what is the answer?

Accepted Answer

$$1,046 \ \mathrm{J}$$

Question 17

Which of the following is a correct example of a chemical change?

Accepted Answer

Baking a cake

Question 18

Which of the following is the correct formula for converting Celsius to Kelvin?

Accepted Answer

$$K = ^\circ \mathrm{C} + 273.15$$

Question 19

Which of the following is a correct statement about the difference between a theory and a law in science?

Accepted Answer

A theory explains why phenomena occur, while a law describes what happens.

Question 20

A student has a block of metal with a mass of $$50.0 \ \mathrm{g}$$ and a density of $$5.00 \ \mathrm{g}/\mathrm{mL}. $$What is the volume of the block?

Accepted Answer

$$10.0 \ \mathrm{mL}$$

General Chemistry I: Essential Concepts, Conversions, and Equations

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