Unit 2 practice test

Which of the following elements form a nonpolar covalent bond?

• Cl-Cl

• K-O

• C-Cl

• Ca-Cl

Answer explanation

The Cl-Cl bond is nonpolar because it involves two identical chlorine atoms sharing electrons equally. In contrast, K-O, C-Cl, and Ca-Cl bonds involve different elements, leading to unequal sharing and polar bonds.

Tags

NGSS.HS-PS1-1

What is the formula of calcium phosphate, which is made up of the ions Mg²⁺ and PO₃^3-?

• Mg₃PO₃

• Mg₆PO₃

• Mg₃(PO₃)₂

• Mg2(PO3)3

Answer explanation

Magnesium phosphate is formed from Mg²⁺ and PO₃^3-. To balance the charges, three Mg²⁺ ions (total +6) combine with two PO₃^3- ions (total -6), resulting in Mg₃(PO₃)₂.

Tags

NGSS.HS-PS1-2

Which of the following is the correct name for N₃O₅?

• nitrous dioxide

• trintrogen pentoxide

• nitrogen dioxide

• nitrate oxide

Answer explanation

N3O5 consists of three nitrogen (N) atoms and five oxygen (O) atoms. The correct nomenclature for this compound is trinitrogen pentoxide, reflecting the number of each type of atom present.

What is the correct formula for the compound formed between beryllium and nitrogen?

• Be₃N₂

• BeN

• Be₃N

• Be₂N₃

Answer explanation

Beryllium (Be) has a +2 charge and nitrogen (N) has a -3 charge. To balance the charges, we need 3 Be ions for every 2 N ions, resulting in the formula Be3N2, which is the correct compound formed between beryllium and nitrogen.

Tags

NGSS.HS-PS1-1

NGSS.HS-PS1-2

Which of the following formulas is not correct?

• Ba₂O₃

• Al₂(SO₄)₃

• NaClO₃

• Mg(NO₃)₂

• K₃PO₄

Answer explanation

Ba2O3 is incorrect because barium oxide should be BaO, as barium has a +2 charge and oxygen has a -2 charge, requiring a 1:1 ratio. The other formulas are correct representations of their respective compounds.

What is the correct name for FeBr₃?

• iron (III) bromide

• iron bromide

• iron tribromide

• iron bromic acid

• iron (II) bromide

Answer explanation

FeBr₃ contains iron in the +3 oxidation state, hence it is named iron (III) bromide. The other options either misrepresent the oxidation state or the compound's composition.

if you have the compound Cu₃PO₄, what is the charge of a cation?

• 1

• 3

• -1

• -3

Answer explanation

In Cu3PO4, the phosphate ion (PO4) has a charge of -3. To balance this, the total positive charge from the cations (Cu) must be +3. Since there are 3 Cu ions, each must have a charge of +1.

Tags

NGSS.HS-PS1-1

What would the name you would use for the second element be if you had the compound CH₄​​​​?

• tetrahydride

• dihydrogen

• hydride

• hydride (IV)

• heptahydride

Answer explanation

The compound CH4 is methane, which consists of one carbon atom and four hydrogen atoms. The prefix 'tetra-' indicates four, making 'tetrahydride' the correct name for the second element in this compound.

What is the charge of the unknown atoms in the formula X₂O?

• 1

• 2

• 4

• 3

• -2

Answer explanation

In the formula X2O, oxygen typically has a charge of -2. To balance the charges, the two X atoms must each have a charge of +1, making the total charge from X equal +2, which balances the -2 from oxygen.

Tags

NGSS.HS-PS1-1

What is the charge of the unknown atoms in the formula Ga₂(X)₃?

• -1

• -2

• -3

• -4

• 2

Answer explanation

In the formula Al(X)3, aluminum (Al) has a +3 charge. To balance this, the unknown atoms (X) must collectively have a -3 charge. Since there are three X atoms, each must have a charge of -1.

Tags

NGSS.HS-PS1-1

NGSS.HS-PS1-2