Chemistry

• A. a hypothesis

• B. a conclusion

• C. an observation

• D. a theory

• Be 4/5

• Be 4/9

• Be 5/4

• Be 9/4

Tags

NGSS.HS-PS1-1

3. Chlorine is a highly reactive element. It tends to gain one electron to become more stable. How does gaining one electron make chlorine more stable?

• A. Stability is increased with greater mass

• B. Mobility is reduced in atoms with extra electrons

• C. The outer energy level becomes the same as a noble gas.

• D. The most stable ratio of electrons to protons is achieved.

Tags

NGSS.HS-PS1-1

NGSS.HS-PS1-2

4. The element lanthanum has an isotope with an atomic mass of 138.9 amu and an abundance of 99.91%. A second isotope has an atomic mass of 137.9 amu and an abundance of 0.09%. What is the average atomic mass of lanthanum?

• A. 138.4 amu

• B. 138.8 amu

• C. 138.9 amu

• D. 139.0 amu

A carbon nucleus has a total mass of 12.0000 amu. When the individual masses of the particles in the nucleus are added separately, the total mass is 12.0956 amu. What is the reason for the difference in masses?

• A. Mass is converted into chemical energy

• B. Mass is converted into the nuclear binding energy

• C. Nuclear radiation has been given off in the form of small particles

• D. Each particle gains an electron when separated, increasing the mass

Tags

NGSS.HS-PS1-8

Which statement explains why MOST of the mass of an atom is contained in the relatively small nucleus?

• A. Atoms are composed of less dense subunits than the nucleus.

• B. Protons and neutrons have more mass than electrons.

• C. The nucleus is located at the center of an atom.

• D. Atoms are composed of mostly empty space.

• A. The chemical properties are different for each element.

• B. The atomic number is different for each element.

• C. They are allotropes of the same element

• D. They are isotopes of the same element.

Tags

NGSS.MS-PS1-1

9. Which force is responsible for holding the nucleus of an atom together?

• A. electromagnetic force

• B. gravitational force

• C. strong force

• D. weak force

• 32.06 amu

• 32.39 amu

• 33.75 amu

• 34.12 amu

Physical or chemical change?
cutting a piece of paper in half

• Physical
• Chemical