STAAR Science

Which of these formulas contain equal numbers of nitrogen atoms?

• Formulas I and III

• Formulas I and IV

• Formulas II and III

• Formulas I, II, and V

Tags

NGSS.MS-PS1-1

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?

• 6

• 12

• 24

• 36

Tags

NGSS.MS-PS1-1

NGSS.MS-PS1-5

The chemical formula for sodium sulfate is Na₂SO₄. How many sulfur atoms are in the formula for sodium sulfate?

• 1

• 2

• 6

• 7

Tags

NGSS.MS-PS1-1

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

• The color of the protein

• The number of molecules in each sequence that makes up a protein

• The physical arrangement of atoms in the structure of the protein

• The number of atoms of each element in the protein

Tags

NGSS.MS-PS1-1

As part of an investigation, students combined substances in a beaker to observe chemical reactions. They performed two procedures. They measured the mass of each substance before and after each reaction. The table shows their observations. Assuming the students did not make any careless errors, what likely explains these changes in mass?

• Procedure 1: All the reactants were liquids that evaporated.

  Procedure 2: A gas was formed as one product, and it escaped into the air.

• Procedure 1: One of the reactants was converted to thermal energy.

  Procedure 2: All the products were liquids.

• Procedure 1: The reactants were liquids with different densities.

  Procedure 2: The reactants were combined into only one product.

• Procedure 1: One of the products was a gas that escaped into the air.

  Procedure 2: A gas from the air reacted with one of the other reactants.

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

A silver ring reacts with compounds containing sulfur in the air to form silver sulfide, a black substance that makes up the tarnish on the surface of silver objects. To remove the tarnish from the ring, students placed it in a pan lined with aluminum foil and added hot water. Baking soda was added to the hot water and stirred. Which observation of this process provides evidence of a chemical reaction?

• Hot water heated the aluminum foil.

• The liquid solution changed color.

• The pan was lined with aluminum foil.

• The hot water cooled.

Tags

NGSS.MS-PS1-2

A chemical reaction in which calcium carbonate, CaCO₃, is decomposed results in the production of two simpler compounds.

What mass of calcium carbonate, to the nearest hundredth of a gram, is decomposed in this reaction?

• 49.97

• 28.00

• 21.97

• 6.03

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

Coal contains carbon and other elements. Carbon dioxide forms when coal burns in the presence of oxygen. Which of these is the best evidence that a chemical reaction occurs when coal burns?

• The shape of the coal changes.

• Oxygen is present.

• A new substance is produced.

• Coal is made up of more than one element.

Tags

NGSS.MS-PS1-2

For an investigation a student poured a blue solution of CuSO₄ into a beaker. The student placed a shiny, silver-colored strip of zinc metal in the solution and observed the changes. The student inferred that a chemical reaction occurred. What evidence supports this inference?

• A dark solid formed on the zinc metal.

• The zinc metal remained silver-colored and shiny.

• The CuSO₄ solution turned blue when the zinc metal was added.

• None of these

Tags

NGSS.MS-PS1-2

A balance and a graduated cylinder are used to determine the density of a mineral sample. The sample has a mass of 14.7 g and a volume of 2.2 cm³. What is the density of the mineral sample?

• 0.15 g/cm³

• 32 g/cm³

• 13 g/cm³

• 6.7 g/cm³