Water is a compound of hydrogen and oxygen. If you were able to take water and separate it into hydrogen and oxygen, what would the smallest unit of each component be?

• a molecule of oxygen and 2 molecules of hydrogen

• an atom of oxygen and a molecule of hydrogen

• an atom of oxygen and 2 atoms of hydrogen

• an atom of hydrogen and a molecule of oxygen

Tags

NGSS.MS-PS1-1

When solid X is heated, it breaks up into gas Y and another solid Z. The solids X and Z and the gas Y are all pure substances. Based on this information alone, which substance or substances must be compounds?

• X Only

• Z Only

• X and Z

• X and Y Only

Tags

NGSS.MS-PS1-1

NGSS.MS-PS1-2

A class performed an experiment to investigate mass changes in a closed system. The teacher divided the class into pairs and gave each pair either a physical or chemical change to perform. Multiple groups investigated a change of state, dissolving salt into water, heating copper & sulfur, and dissolving alka-seltzer & water. The mass of reactants was measured before the change and the mass of the products was measured after the change was complete. The mass of the reactants was subtracted from the mass of the products. The teacher collected the data from each pair and calculated the averages to make the following graph. Why did the teacher use data from all the groups to make a single graph?

• To ensure the validity of the data.

• To ensure she could read everyone’s results.

• To ensure everyone’s graph looked the same.

• To ensure the experiment was conducted correctly.

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

When silver nitrate is added to saltwater, white powder-like solid appears in the beaker. Which of the following best describes the result?

• A physical change occurred as indicated by the bubbling.

• A chemical change occurred as indicated by the precipitate.

• A chemical change occurred as indicated by a change in state.

• A physical change occurred as indicated by the formation of a gas.

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

JJ Thompson’s theory thought that atoms were composed purely of negatively charged electrons. This model became known as the plum pudding model. What does current atomic theory propose?

• Electrons are in shells surrounding the nucleus.

• Electrons are found in the nucleus of an atom.

• An atom’s nucleus contains both protons and neutrons.

• Both A and C are true statements about what we know about atoms.

Tags

NGSS.HS-PS1-8

Reynalda was asked by a classmate why she would place hydrogen in the first column of the periodic table. Which of the following reasons could she give as a response?

I. Hydrogen combines with chlorine in the same atomic ratio as sodium.

II. Hydrogen is a gas at room temperature.

III. Hydrogen forms diatomic molecules.

• I and II

• II and III

• I only

• III only

In the diagram below “D” represents one valence electron of the atom Beryllium. The valence electrons help to determine the number of bonds an atom can make with another to form a compound. What would the chemical formula be for Beryllium combining with the element Chlorine?

• Be₂Cl

• BeCl

• BeCl₂

• Be₂Cl₂

Tags

NGSS.MS-PS1-1

Which piece of information in a square on the periodic table represents the number of protons in an atom.

• Symbol

• Atomic Number

• Atomic Mass

• Element Name

Molecular model kits are used to model elements, compounds, and molecules. A model of water is shown below. What is the benefit provided to scientists using this model?

• The model provides information about the structure of an atom, helping scientists determine the locations of protons and electrons.

• The model provides information about the ways the atoms are arranged, helping scientists identify chemical bonding opportunities.

• The model provides information about the actual size of chemical substances, helping scientists determine the volume of the molecules.

• The model provides information about the abundance of atoms in the universe, helping scientists discover additional elements in space.

Tags

NGSS.MS-PS1-1

Which piece of information in a square on the periodic table represents the number of protons and neutrons in an atom?

• Symbol

• Atomic Number

• Atomic Mass

• Element Name