Q: A student wants to convert $$250\ \mathrm{mg} to $$kilograms using scientific notation. What is the correct answer?

$$2.5 \times 10$$^{-4}$$\ \mathrm{kg}$$

Question 1

A student measures the mass of a metal sample as $$12.45\ \mathrm{g}$$ and its volume as $$4.1\ \mathrm{cm}^3. $$What is the density of the metal, reported with the correct number of significant figures?

Accepted Answer

$$3.0\ \mathrm{g/cm}^3$$

Question 2

Which of the following best describes a chemical change?

Accepted Answer

Iron rusting in moist air

Question 3

A sample of gasoline has a density of $$0.74\ \mathrm{g/mL}. $$What is the mass, in kilograms, of $$2.50\ \mathrm{L} of $$gasoline? ($$1\ \mathrm{L} = 1000\ \mathrm{mL})$$

Accepted Answer

$$1.85\ \mathrm{kg}$$

Question 4

Which of the following statements is an example of a scientific law?

Accepted Answer

The total mass of substances does not change during a chemical reaction.

Question 5

Convert $$5.60\ \mathrm{km} to $$centimeters using dimensional analysis.

Accepted Answer

$$56,000\ \mathrm{cm}$$

Question 6

Which of the following is a heterogeneous mixture?

Accepted Answer

Salad with lettuce, tomatoes, and cucumbers

Question 7

A reaction absorbs $$150.0\ \mathrm{J} of $$heat from its surroundings. Which term best describes this process?

Accepted Answer

Endothermic

Question 8

A beaker contains $$100.0\ \mathrm{g} of $$water at $$25.0^\circ\mathrm{C}. $$How much heat (in joules) is required to raise the temperature to $$75.0^\circ\mathrm{C}$$? (Specific heat of water $$= 4.18\ \mathrm{J/g\cdot ^\circ C})$$

Accepted Answer

$$20,900\ \mathrm{J}$$

Question 9

Which of the following is a correct statement of the law of conservation of energy?

Accepted Answer

Energy can neither be created nor destroyed, only transformed from one form to another.

Question 10

A student records the following measurements: $$2.50\ \mathrm{cm}$$, $$2.5\ \mathrm{cm}$$, and $$2.500\ \mathrm{cm}. $$Which statement is correct regarding significant figures?

Accepted Answer

$$2.500\ \mathrm{cm}$$ has the most significant figures.

Question 11

Which of the following best describes a crystalline solid?

Accepted Answer

A solid with particles arranged in a regular, repeating pattern

Question 12

A sample of gas occupies $$2.00\ \mathrm{L} at$$ $$25^\circ\mathrm{C}. $$What is this temperature in Kelvin?

Accepted Answer

$$298\ \mathrm{K}$$

Question 13

Which of the following is an example of potential energy?

Accepted Answer

A compressed spring

Question 14

Which of the following is a compound?

Accepted Answer

Sodium chloride ($$\mathrm{NaCl})$$

Question 15

A student needs to convert $$3.00\ \mathrm{m}^2 to$$ $$\mathrm{cm}^2. $$What is the correct value?

Accepted Answer

$$300,000\ \mathrm{cm}^2$$

Question 16

Which of the following is a physical property?

Accepted Answer

Melting point

Question 17

A chemical reaction produces $$12.0\ \mathrm{g} of $$product from $$10.0\ \mathrm{g} of $$reactant A and $$2.0\ \mathrm{g} of $$reactant B. Which law does this observation support?

Accepted Answer

Law of conservation of mass

Question 18

Which of the following is the correct SI unit for measuring energy?

Accepted Answer

Joule

Question 19

A student wants to convert $$250\ \mathrm{mg} to $$kilograms using scientific notation. What is the correct answer?

Accepted Answer

$$2.5 	imes 10$$^{-4}$$\ \mathrm{kg}$$

Question 20

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

Accepted Answer

A tentative explanation that can be tested by experiments

Introductory Chemistry: Measurement, Matter, and Energy

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