Cde Science

A researcher wants to experiment with an element that reacts like phosphorus (P) but has a greater atomic mass. Which element should the researcher select for the experiment?

• Nitrogen (N)

• Sulfur (S)

• Arsenic (As)

• Silicon (Si)

Which of the following best describes an electron?

• It has no charge and about the same mass as a proton.

• It has a negative charge and much less mass than a proton.

• It has a positive charge and much more mass than a neutron.

• It has a negative charge and about the same mass as a neutron.

Tags

NGSS.MS-PS2-3

A scientist spilled a few drops of dilute hydrochloric acid (HCl) on a lab table. For safety purposes, the scientist sprinkled some baking soda (NaHCO₃) onto the spill. Which observation would provide the best evidence that a chemical reaction occurred?

• The baking soda and hydrochloric acid combined, and bubbles formed.

• The baking soda absorbed the hydrochloric acid.

• Some of the baking soda dissolved in the hydrochloric acid.

• The hydrochloric acid evaporated, leaving only the baking soda.

Tags

NGSS.MS-PS1-2

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

A teacher asks a student to write the chemical equation for photosynthesis. The student’s response is shown below. The equation is not balanced correctly. Which of these is a balanced equation for photosynthesis?

• 
• 
• 
• 

Tags

NGSS.MS-LS1-6

NGSS.MS-PS1-5

When trying to identify an unknown element, a scientist determines what other elements the unknown element reacts with chemically. Which property of the unknown element determines the other elements it reacts with?

• The total number of neutrons in the unknown element

• The total number of particles in the nuckleus of the unknown element

• The number of protons in the nucleus of the unknown element

• The number of valence electrons in the unknown wlwment

Tags

NGSS.HS-PS1-1

NGSS.HS-PS1-2

The model of the periodic table below shows the locations of four elements. A student is asked to identify an element that is a pale-yellow brittle solid and does not conduct electricity. At which location in this periodic table would the element most likely be found?

• 1

• 2

• 3

• 4

During an investigation, a student combined the two clear, colorless solutions shown below. The student observed that the temperature changed from 25°C to 23°C when the solutions were combined and that a white substance rapidly formed and settled to the bottom of the container. What most likely happened to produce these results?

• One of the orginal compounds came out of solution

• The solutions reacted chemically

• Some of the water frose into ice crystals

• Rapid evaporation of water occurred, leaving a solid

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 that one element

Tags

NGSS.MS-PS1-2

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

• 21

• 3

• 51.989

• 105.953