Unit 4 Post Assessment Remediation (PAR)

In the 19th century, Dmitri Mendeleev predicted the existence of a then unknown element X with an oxide formula X₂O₃. Element X could be which of the following?

• beryllium

• gallium

• sodium

• germanium

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NGSS.HS-PS1-1

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Choose the group that corresponds to each element.

• Chlorine

• Alkali metal

• Barium

• Transition Metal

• Rubidium

• Halogen

• Cobalt

• Alkaline earth metal

• Xenon

• Noble gas

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NGSS.HS-PS1-1

Which element has chemical properties that are most similar to the chemical properties of sodium?

• Mg

• K

• Se

• Cl

At STP, which element is malleable and a good conductor of electricity?

• xenon

• silicon

• platinum

• hydrogen

At STP, which element is solid, brittle, and a poor conductor of electricity?

• Al

• K

• Ne

• S

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Diamond and graphite have different properties because they have different

• crystal structures

• electronegativities

• numbers of protons per atom

• numbers of valence electrons per atom

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NGSS.MS-PS1-1

Which changes in both charge and radius occur when an atom loses an electron?

• A negative ion is formed with a smaller radius than the atom.

• A negative ion is formed with a larger radius than the atom.

• A positive ion is formed with a smaller radius than the atom.

• A positive ion is formed with a larger radius than the atom.

An oxide ion, O²⁻, has the same electron configuration as an atom of which noble gas?

• helium

• neon

• argon

• krypton

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NGSS.HS-PS1-1

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Which element has a melting point higher than the melting point of rhenium?

• iridium

• osmium

• tantalum

• tungsten

Which of the following statements is true going down a group?

• the electronegativity decreases because the number of shielding electrons remains the same

• the electronegativity decreases because the number of shielding electrons increases

• the electronegativity increases because the number of shielding electrons remains the same

• the electronegativity increases because the number of shielding electrons increases

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NGSS.HS-PS1-1

NGSS.HS-PS1-2