Which electron shell contains the valence electrons of a radium atom in the ground state?

• the sixth shell

• the second shell

• the seventh shell

• the eighteenth shell

Tags

NGSS.HS-PS1-1

Each diagram represents the nucleus of an atom. How many different elements are represented by the diagram?

• 1

• 2

• 3

• 4

Tags

NGSS.HS-PS1-8

Chlorine and element X have similar chemical properties. An atom of element X could have an electron configuration of

• 2-2

• 2-8-1

• 2-8-8

• 2-8-18-7

Tags

NGSS.HS-PS1-1

NGSS.HS-PS1-2

Which group of elements contains a metalloid?

• Group 8

• Group 2

• Group 16

• Group 18

Which Lewis electron-dot diagram represents a fluoride ion

• 
• 
• 
• 

Tags

NGSS.HS-PS1-1

NGSS.HS-PS1-2

In the formula for the compound XCl₄, the X could represent

• C

• H

• Mg

• Zn

Tags

NGSS.HS-PS1-1

NGSS.HS-PS1-2

Given the balanced equation representing a reaction:

4Al(s) + 3O₂(g) --> 2Al₂O₃(s)

How many moles of Al(s) react completely with 4.50 moles of O₂(g) to produce 3.00 moles of Al₂O₃(s)?

• 1.50 mol

• 2.00 mol

• 6.00 mol

• 4.00 mol

What is the percent composition by mass of oxygen in Ca(NO₃)₂ (gram-formula mass = 164 g/mol)?

• 9.8%

• 29%

• 48%

• 59%

Compared to a 1.0-mole sample of NaCl(s), a 1.0-mole sample of NaCl(l) has a different

• number of ions

• empirical formula

• gram-formula mass

• electrical conductivity

Tags

NGSS.HS-PS2-5

Which ion combines with Ba²⁺ to form a compound that is most soluble in water?

• S^2-

• OH^-

• CO₃^2-

• SO₄^2-