Category 1 Science STAAR Review

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 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

Which statement accurately describes the atoms of a specific element?

• An Indium, In, Atom contains 115 protons inside the nucleus and 49 neutrons outside the nucleus.

• A scandium, Sc, atom contain 45 electrons outside the nucleus and 21 neutrons inside the nucleus.

• An aluminum, Al, atom contains 27 electrons and 27 protons inside the nucleus.

• A zinc, Zn, atom contain 30 protons inside the nucleus and 30 electrons outside the nucleus.

Tags

NGSS.MS-PS1-1

What is the total number of protons, neutrons, and electrons in a cadmium, Cd, atom that has a mass number of 112?

• 160

• 112

• 48

• 64

What is the difference between the number of electrons in an atom of selenium, Se, and the number of electrons of aluminum, Al?

• 21

• 52

• 13

• 34

An atom of a certain element has 36 protons, 36 electrons, and a mass number of 84. At room temperature this element is a very stable gas. How many neutrons are in this atom?

• 48

• 84

• 72

• 36

Tags

NGSS.MS-PS1-1

In the early 1900s many scientists thought that an atom consisted of a positive substance with negative charges scattered throughout the substance. Then Ernest Rutherford completed an experiment that changed the concept of the atom. His discovery led to the understanding that an atom consists mostly of empty space with -

• protons orbiting a dense nucleus made of electrons and neutrons

• electrons orbiting a dense nucleus made of protons and neutrons

• neutrons and protons orbiting a cloud of electrons

• electrons and protons orbiting a cloud of neutrons

Tags

NGSS.HS-PS1-8