Question 1

Which of the following best describes the difference between a scientific law and a scientific theory?

Accepted Answer

A scientific law describes a consistent relationship observed in nature, while a scientific theory explains why those relationships exist.

Question 2

Antoine Lavoisier is credited with which fundamental chemical law, and what does it state?

Accepted Answer

Law of Conservation of Mass: In a chemical reaction, mass is neither created nor destroyed.

Question 3

A student measures the mass of a sample as $$2.50 	imes 10^2$ grams. Express this value in standard notation.

Accepted Answer

$$250$$ grams

Question 4

Which of the following statements correctly distinguishes between mass and weight?

Accepted Answer

Mass is the amount of matter in an object, while weight is the force of gravity acting on that mass.

Question 5

A sample of liquid has a mass of $$45.0 g $$and a volume of $$15.0 mL. $$What is its density?

Accepted Answer

$$3.00 g/mL$$

Question 6

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

Accepted Answer

A salad with lettuce, tomatoes, and cucumbers

Question 7

Which process is best for separating a mixture of sand and saltwater?

Accepted Answer

Filtration

Question 8

Which of the following changes is a chemical change?

Accepted Answer

Burning a piece of wood

Question 9

A reaction absorbs heat from its surroundings. Which term best describes this process?

Accepted Answer

Endothermic

Question 10

Convert $$25.0$$ °C to Kelvin using the correct formula.

Accepted Answer

$$298.15 K$$

Question 11

Which of the following best describes Rutherford’s nuclear theory of the atom?

Accepted Answer

Most of the atom’s mass and all of its positive charge are concentrated in a small nucleus.

Question 12

An atom has $$11$$ protons, $$12$$ neutrons, and $$10$$ electrons. What is its charge and what is its identity?

Accepted Answer

Sodium ion, $$+1$$ charge

Question 13

Which of the following statements about isotopes is correct?

Accepted Answer

Isotopes of an element have the same number of protons but different numbers of neutrons.

Question 14

A sample of water is heated from $$20.0$$ °C to $$80.0$$ °C. If the mass of water is $$100.0 g $$and the specific heat capacity is $$4.18 J/g$$·°C, how much heat is absorbed?

Accepted Answer

$$25,080 J$$

Question 15

Which of the following is a physical property?

Accepted Answer

Boiling point

Question 16

Which of the following best describes a compound?

Accepted Answer

A substance composed of two or more elements chemically combined in a fixed ratio

Question 17

Which of the following is the correct relationship between Celsius and Fahrenheit temperatures?

Accepted Answer

$$F = \frac{9}{5}C + 32$$

Question 18

A $$50.0 mL $$sample of ethanol (density $$0.789 g/mL) is $$spilled. What is the mass of the ethanol lost?

Accepted Answer

$$39.5 g$$

Question 19

Which of the following best describes an exothermic reaction?

Accepted Answer

A reaction that releases energy to its surroundings, often as heat

Question 20

Which of the following is a correct statement of the Law of Conservation of Mass as applied to a chemical reaction in a closed system?

Accepted Answer

The total mass of reactants equals the total mass of products.

Exam 1 Study Guide: Foundations of Chemistry (Chapters 1–4)

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