Particles

Question 1

Which is the smallest particle?
An atom

A molecule

A speck of dust

Answer 1

The smallest particle is an atom.

Question 2

What is the correct symbol for magnesium?

Answer 2

The symbol for magnesium is Mg.

Question 3

Which statement about atoms and molecules is correct?
Elements always exist as separate atoms

Elements always exist as pairs of atoms called molecules

Elements and compounds can exist as molecules

Answer 3

Elements and compounds can exist as molecules.

Question 4

How many different atoms are there in a compound?

Answer 4

There are two or more atoms in a compound.

Question 5

Approximately how many elements are there?

Answer 5

There are approximately 100 elements listed on the periodic table.

Question 6

Which one is a compound?
Water

Hydrogen

Helium

Answer 6

Water is a compound because it is made from hydrogen and oxygen.

Question 7

What contains two carbon atoms and six hydrogen atoms?
CH4

C2H6

C2H4

Answer 7

C2H6 contains six hydrogen atoms.

Question 8

Which of these contains four hydrogen atoms?
CH3OH

H2O

H2O2

Answer 8

CH3OH contains four hydrogen atoms

Question 9

How many atoms are there in total in a molecule of sulfur trioxide, SO3?

Answer 9

There are four atoms in total in a molecule of sulfur trioxide.

Question 10

Why does air not have a definite formula?

Answer 10

Air is a mixture, so it doesn’t have a definite formula.

Question 11

Is this an element, mixture or compound?

The two atoms are joined, but there are still only one type.

Answer 11

This diagram shows an element.

Question 12

Is water an element, compound or mixture?

Answer 12

Water is a compound.

Question 13

What is the name of the process that occurs when salt is added to water and then stirred until the solid is no longer visible?

Answer 13

Dissolving occurs when solid salt is added to water and stirred.

Question 14

Is air an element, compound or mixture?

Answer 14

Air is a mixture. It contains several elements and compounds.

Question 15

In what type of substance does diffusion take place most quickly?

Answer 15

Diffusion occurs most quickly in gases.

Question 16

In a solution of copper sulfate, what is the solvent?

Answer 16

Water is the solvent in a solution of copper sulfate.

Question 17

What name is given to a substance that contains two types of atom that are not chemically joined together?

Answer 17

When two substances are mixed but not chemically joined to each other, they form a mixture.

Question 18

In a salt solution, what is the solute?

Answer 18

The solid in a solution is the solute so in this case it is the salt.

Question 19

What process allows you to smell freshly baked bread in a supermarket, even when you are far from the bakery aisle?

Answer 19

Diffusion allows the smell particles to spread through the air and reach your nose.

Question 20

What happens to the boiling point of water when salt is added to it?

Answer 20

Impurities in a substance will change its boiling point.