Counting Atoms Practice (STAAR Questions)

Barium sulfate, BaSO_4, is a white crystalline solid that is insoluble in water. It is used by doctors to diagnose problems with the digestive system. Barium hydroxide, Ba(OH)₂, is also a white crystalline solid that is used in wastewater treatment. How many more oxygen atoms are represented in the formula for barium sulfate than in the formula for barium hydroxide?

The names and chemical formulas of four substances are shown in the chart. Which substance listed in the chart is made up of the most atoms? Click on the name of the substance.

Tags

NGSS.MS-PS1-1

A student is using colored beads to make a model of aluminum sulfate, Al₂(SO₄)₃. Aluminum atoms are represented by blue beads, sulfur atoms by yellow beads, and oxygen atoms by green beads. What combination of beads should the student use for the model?

• 6 blue, 3 yellow, and 7 green

• 2 blue, 1 yellow, and 4 green

• 2 blue, 3 yellow, and 12 green

• 6 blue, 12 yellow, and 12 green

Tags

NGSS.MS-PS1-1

Strontium phosphate, Sr₃(PO₄)₂, is a crystalline substance used in medicine and industry. How many phosphorus atoms are represented in the formula Sr₃(PO₄)₂?

The table shows the chemical formulas for four substances. Which substances have the same number of carbon atoms? 

• Substance 1

• Substance 2

• Substance 3

• Substance 4

The equation below represents a chemical reaction that occurs in living cells.

C₆H₁₂O₆ + 6O₂ --------> 6CO₂ + 6H₂O + energy

How many atoms are represented in the reactants of this equation?

Tags

NGSS.HS-PS1-7

Which information could a student determine from only the chemical formula?

• The number of atoms of each element in the chemical formula.

• The color of the elements.

• The number of molecules in each sequence that makes up a chemical formula.

• The physical arrangement of atoms in the structure of the chemical formula.

Tags

NGSS.MS-PS1-1

What is the mass of 2H₂O from the product?

Tags

NGSS.HS-PS1-7

A manufacturer selected a metal to use in producing a lightweight button for clothing. A metal that has a density of 2.71 g/cm³ was selected.

• Metal 1

• Metal 2

• Metal 3

• Metal 4

Which of the atom models below represents a reactive metal?

• Model A

• Model B

• Model C

• Model D

Tags

NGSS.HS-PS1-1

NGSS.HS-PS1-2