Question 1

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

Accepted Answer

A scientific law describes a consistent relationship observed in nature, often expressed mathematically, while a scientific theory explains why those relationships exist based on evidence and reasoning.

Question 2

A student measures the mass of a sample three times and records the values: 5.12 g, 5.13 g, and 5.11 g. The true mass is 5.50 g. Which statement best describes the student's measurements?

Accepted Answer

The measurements are precise but not accurate.

Question 3

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

Accepted Answer

A piece of iron rusts when left outside.

Question 4

A solution is prepared by dissolving 10.0 g of NaCl in 90.0 g of water. Which term best describes this mixture?

Accepted Answer

Homogeneous mixture

Question 5

Which of the following best describes the Law of Conservation of Mass?

Accepted Answer

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

Question 6

A student records a temperature of $$25.0\ ^\circ\mathrm{C}. $$What is this temperature in Kelvin?

Accepted Answer

$$298.2\ \mathrm{K}$$

Question 7

Which of the following is the correct formula for calculating the density ($$d) of a $$substance?

Accepted Answer

$$d = \frac{m}{V}$$

Question 8

A sample of metal has a mass of $$45.0\ \mathrm{g}$$ and a volume of $$15.0\ \mathrm{mL}. $$What is its density?

Accepted Answer

$$3.00\ \mathrm{g/mL}$$

Question 9

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 10

Which of the following is a correct example of a physical property?

Accepted Answer

The melting point of ice is $$0\ ^\circ\mathrm{C}.$$

Question 11

A student needs to measure $$25.00\ \mathrm{mL} of a $$liquid as precisely as possible. Which piece of glassware should they use?

Accepted Answer

A $$25.00\ \mathrm{mL}$$ graduated cylinder

Question 12

Which of the following is an example of an endothermic process?

Accepted Answer

Ice melting to form liquid water

Question 13

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

Accepted Answer

Endothermic

Question 14

Which of the following is the correct equation for calculating heat transfer ($$q) $$when a substance changes temperature?

Accepted Answer

$$q = mc\Delta T$$

Question 15

A $$50.0\ \mathrm{g}$$ sample of water is heated from $$20.0\ ^\circ\mathrm{C} to$$ $$30.0\ ^\circ\mathrm{C}. $$The specific heat capacity of water is $$4.18\ \mathrm{J/g\ ^\circ C}. $$How much heat ($$q) is $$absorbed?

Accepted Answer

$$2090\ \mathrm{J}$$

Question 16

Which of the following best describes a heterogeneous mixture?

Accepted Answer

A mixture in which the composition is not uniform throughout, such as sand in water.

Question 17

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

Accepted Answer

Kilogram ($$\mathrm{kg})$$

Question 18

A student is asked to convert $$0.00560 to $$scientific notation. Which is the correct answer?

Accepted Answer

$$5.60 	imes 10$$^{-3}$$

Question 19

Which of the following statements about the periodic table is correct?

Accepted Answer

Elements in the same group (vertical column) have similar chemical properties.

Question 20

A sample contains $$80.0\%$$ isotope A (mass $$10.0\ \mathrm{amu}) $$and $$20.0\%$$ isotope B (mass $$11.0\ \mathrm{amu}). $$What is the average atomic mass?

Accepted Answer

$$10.2\ \mathrm{amu}$$

Introduction to Chemistry: Core Concepts and Laboratory Skills

Guida di studio - Domande di pratica

Study guide - Flashcard