7.6ABCDE Exploring Matter and Solutions Review

Oliver and Abigail are having a friendly debate about chemistry. Oliver says, "Elements are like the building blocks of the universe, made of atoms!" Abigail counters, "But compounds are like the recipes, made of molecules!" Who is correct?

• Elements are made of molecules, while compounds are made of atoms.

• Elements are made of atoms, while compounds are made of molecules.

• Both elements and compounds are made of molecules.

• Both elements and compounds are made of atoms.

Answer explanation

Elements consist of single types of atoms, while compounds are formed from two or more different atoms bonded together, creating molecules. Thus, the correct statement is that elements are made of atoms, while compounds are made of molecules.

Hey Science Explorers! David and Grace are on a quest to find the magical element that keeps us breathing. Can you help them by identifying the chemical symbol for Oxygen?

• O

• Ox

• Oy

• Om

Answer explanation

The chemical symbol for Oxygen is 'O'. This is the standard notation used in chemistry to represent the element, while 'Ox', 'Oy', and 'Om' are not recognized symbols for Oxygen.

• 1

• 2

• 3

• 4

Answer explanation

In the chemical formula H₂O, the subscript '2' indicates there are 2 hydrogen atoms. Therefore, the correct answer is 2.

Tags

NGSS.MS-PS1-1

During a science quiz, Sophia was asked a tricky question: "What is the atomic number of the element that forms the backbone of all life on Earth, known as Carbon?" Can you help her out?

• 6

• 12

• 14

• 16

Answer explanation

The atomic number of an element is defined as the number of protons in its nucleus. Carbon has 6 protons, which gives it an atomic number of 6. Therefore, the correct answer is 6.

During a science experiment, James and Abigail are observing different processes. Which of the following processes observed by them is a chemical change?

• Melting ice

• Burning wood

• Tearing paper

• Dissolving sugar in water

Answer explanation

Burning wood is a chemical change because it transforms the wood into ash and gases through combustion, altering its chemical structure. In contrast, melting ice, tearing paper, and dissolving sugar are physical changes.

Tags

NGSS.MS-PS1-2

Ava and James are having a science experiment competition. Which of the following actions will result in a physical change?

• Rusting of iron

• Baking a cake

• Freezing water

• Digesting food

Answer explanation

Freezing water is a physical change because it involves a change in state from liquid to solid without altering the chemical composition. In contrast, rusting, baking, and digesting involve chemical changes.

During a fun science experiment, Arjun and Evelyn are mixing different substances in water. Can you help them identify what the substance that gets dissolved is called?

• Solvent

• Solute

• Solution

• Concentrate

Answer explanation

In an aqueous solution, the substance that is dissolved is called the solute. The solvent is the liquid that dissolves the solute, while the solution is the mixture of both. Concentrate refers to a solution with a high solute concentration.

Hannah and Arjun are making a saltwater potion for their science project. Can you help them identify the solvent in their magical mixture?

• Salt

• Water

• Air

• Sugar

Answer explanation

In a saltwater solution, water acts as the solvent, dissolving the salt. Salt is the solute, while air and sugar are not components of the solution. Therefore, the correct answer is water.

Imagine Aria is conducting a fun experiment in her kitchen lab! She wants to know how the temperature of water affects the speed at which her favorite sugar cube dissolves. What do you think happens when she heats up the water?

• It decreases the rate of dissolution.

• It has no effect on the rate of dissolution.

• It increases the rate of dissolution.

• It stops the dissolution process.

Answer explanation

Increasing the temperature generally increases the kinetic energy of molecules, leading to more frequent and effective collisions between solute and solvent particles. This enhances the rate of dissolution.

Tags

NGSS.MS-PS1-4

NGSS.MS-PS3-4

Maya and Benjamin are conducting a fun experiment in their science class. They want to find out which factor does NOT affect the rate of dissolution of a solid solute in an aqueous solution. Can you help them figure it out?

• Temperature

• Surface area

• Agitation

• Color of the solute

Answer explanation

The rate of dissolution is influenced by temperature, surface area, and agitation, which enhance solute interaction with solvent. However, the color of the solute does not affect its dissolution rate.