STAAR Science

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 contains 45 electrons outside the nucleus and 21 neutrons inside the nucleus.

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

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

• A Calcium, Ca, atom contains 29 protons inside the nucleus and 29 outside the nucleus

Tags

NGSS.MS-PS1-1

How many protons, neutron, and electrons are present in an atom of hafnium, Hf, with a mass number of 178

• 72 protons, 178 neutrons, 106 electrons

• 72 protons, 106 neutrons, 72 electrons

• 178 protons, 250 neutrons, 72 electrons

• 106 protons, 72 neutrons, 106 electrons

• 80 protons, 121 neutrons, 80 electrons

Tags

NGSS.MS-PS1-1

Based on these drawings, which element is the least reactive?

• Neon, because it has two energy levels with eight electrons in the second level.

• Chlorine, because it has three energy levels with seven electrons in the third energy level.

• Gallium, because it has four energy levels with three electrons in the fourth level.

• Tin, because it has five energy levels with four electrons in the fifth level.

Tags

NGSS.MS-PS1-1

NGSS.MS-PS1-2

Based on the information in the table, which conclusion about the chemical reactivity of these elements is valid?

• Boron is the most reactive because it has the most protons.

• Fluorine is the most reactive because it has 7 electrons in the outer shell.

• Silicon is the most reactive because it has an equal number of protons and neutrons.

• Gallium is the most reactive because it has many more neutrons than protons.

Which table was completed correctly?

• 
• 
• 
• 

Tags

NGSS.HS-PS1-1

How many valence electrons are in an atom of each element in Group 15 in the periodic table?

• 4 valence electrons

• 5 valence electrons

• 6 valence electrons

• 7 valence electrons

• 8 valence electrons

Which chemical reaction involves the fewest oxygen atoms?

• 2AgNO₃ + K₂SO₄ --> Ag₂SO₄ + 2KNO₃

• 4Fe + 6H₂O + 3O₂ --> 4Fe(OH)₃

• 6CO₂ + 6H₂O --> C₆H₁₂O₆ + 6O₂

• C₂H₄ + 3O₂ --> 2CO₂ + 2H₂O

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, 7 green

• 2 blue, 1 yellow, 4 green

• 2 blue, 3 yellow, 12 green

• 6 blue, 12 yellow, 12 green

• 6 blue, 3 yellow, 12 green

Tags

NGSS.MS-PS1-1

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

Based on their observations, can the students correctly conclude that a chemical reaction occurred?

• No, because the metal strip was still visible

• Yes, because a new material of a different color formed on part of the metal strip

• No, because the solution stayed blue

• Yes, because the volume of the blue solution stayed the same

Tags

NGSS.MS-PS1-2