Chemistry, Day 5 - Grade 8 Assignment

The large number in front of a chemical formula is called what, and what does it represent?

• It is called a coefficient and represents the number of molecules or units.

• It is called a subscript and represents the number of atoms in a molecule.

• It is called a superscript and represents the charge of the molecule.

• It is called a prefix and represents the type of chemical bond.

How many molecules are present in Substance 1?

• 2

• 1

• 3

• 4

Tags

NGSS.MS-PS1-1

How many total atoms are present in Substance 3?

• 14

• 10

• 18

• 22

Tags

NGSS.MS-PS1-1

Complete the table for Substances 4 and 5.

• Substance 4: Number of Molecules: 2, Number of Elements: 2, Total Number of Atoms: 10 Substance 5: Number of Molecules: 2, Number of Elements: 3, Total Number of Atoms: 6

• Substance 4: Number of Molecules: 3, Number of Elements: 2, Total Number of Atoms: 8 Substance 5: Number of Molecules: 2, Number of Elements: 2, Total Number of Atoms: 6

• Substance 4: Number of Molecules: 2, Number of Elements: 3, Total Number of Atoms: 10 Substance 5: Number of Molecules: 3, Number of Elements: 3, Total Number of Atoms: 6

• Substance 4: Number of Molecules: 2, Number of Elements: 2, Total Number of Atoms: 8 Substance 5: Number of Molecules: 2, Number of Elements: 3, Total Number of Atoms: 8

Tags

NGSS.MS-PS1-1

Which substances contain the same number of atoms?

• Substance 1 and Substance 4 both have 10 atoms.

• Substance 1 and Substance 3 both have 5 atoms

• Substance 2 and Substance 4 both have 7 atoms.

• Substance 1 and Substance 5 both have 6 atoms.

Tags

NGSS.MS-PS1-1

How many total atoms are represented in the formula for Iron (III) hydroxide, 4Fe(OH)3?

• 28

• 24

• 32

• 16

Tags

NGSS.MS-PS1-1

The chemical formula for potassium nitrate is KNO3. The chemical formula for ammonium nitrate is NH4NO3. How many more nitrogen atoms are represented in the formula for ammonium nitrate than in the formula for potassium nitrate?

• 1

• 2

• 0

• 3

Tags

NGSS.MS-PS1-1

A student is using colored blocks to model barium sulfate, BaSO4. Barium atoms are represented by green blocks, sulfur atoms are represented by blue blocks, and oxygen atoms are represented by red blocks. What combination of blocks should the student use to model two molecules of barium sulfate, 2BaSO4? The student’s model of 2BaSO4 should consist of ______ green blocks, ______ blue blocks, and ______ red blocks.

• 2 green blocks, 2 blue blocks, and 8 red blocks.

• 1 green block, 2 blue blocks, and 4 red blocks.

• 2 green blocks, 1 blue block, and 4 red blocks.

• 2 green blocks, 2 blue blocks, and 4 red blocks.

Tags

NGSS.MS-PS1-1

A space-filling model of methane is shown below. Methane, CH₄ The methane molecule is made up of -

• two atoms

• five elements

• five atoms

• two compounds

Tags

NGSS.MS-PS1-1

Which statement correctly compares elements and compounds?

• A. Elements are represented by chemical formulas, while compounds are represented by chemical symbols.

• B. Elements are represented by chemical symbols, while compounds are represented by chemical formulas.

• C. Elements are made up of different types of atoms, while compounds are made up of the same type of atom.

• D. Elements are classified as pure substances, while compounds are classified as impure substances.