Question 1

Which of the following best describes the difference between Iron(II) oxide and Iron(III) oxide in terms of their chemical formulas?

Accepted Answer

Iron(II) oxide is $$\mathrm{FeO}$$ and Iron(III) oxide is $$\mathrm{Fe_2O_3}.$$

Question 2

A sample contains both Chromium(II) oxide and Chromium(III) oxide. Which pair of formulas correctly represents these compounds?

Accepted Answer

Chromium(II) oxide: $$\mathrm{CrO}$$, Chromium(III) oxide: $$\mathrm{Cr_2O_3}$$

Question 3

Which of the following is the correct formula for chromic oxide, commonly used as a pigment in paints?

Accepted Answer

$$\mathrm{Cr_2O_3}$$

Question 4

If a compound is named iron(III) oxide, what is the oxidation state of iron in this compound?

Accepted Answer

+3

Question 5

A chemist mixes iron filings with oxygen and heats the mixture. Which product is most likely formed?

Accepted Answer

$$\mathrm{Fe_2O_3}$$

Question 6

Which of the following best explains why transition metals like iron and chromium can form multiple oxides?

Accepted Answer

They have variable oxidation states due to their partially filled d orbitals.

Question 7

A student is given a black powder and told it is either iron(II) oxide or iron(III) oxide. Which chemical test could help distinguish between the two?

Accepted Answer

Test for magnetic properties; iron(II) oxide is more magnetic than iron(III) oxide.

Question 8

Which of the following is the correct formula for chromyl chloride, a compound containing chromium in the +6 oxidation state?

Accepted Answer

$$\mathrm{CrO_2Cl_2}$$

Question 9

Iron(III) oxide is used in the thermite reaction to produce molten iron. What is the balanced chemical equation for this reaction?

Accepted Answer

$$\mathrm{Fe_2O_3 + 2Al \rightarrow 2Fe + Al_2O_3}$$

Question 10

Which oxide of iron is most commonly found as rust on iron objects exposed to air and moisture?

Accepted Answer

$$\mathrm{Fe_2O_3}$$

Question 11

A sample of chromium(III) oxide contains 52.0 g of chromium and 24.0 g of oxygen. What is the empirical formula of the compound?

Accepted Answer

$$\mathrm{Cr_2O_3}$$

Question 12

Which of the following statements about iron oxides is correct?

Accepted Answer

Iron(II) oxide is less stable than iron(III) oxide in the presence of oxygen.

Question 13

Which of the following is a correct statement about the naming of transition metal oxides?

Accepted Answer

The Roman numeral in the name indicates the oxidation state of the metal.

Question 14

A student is asked to write the formula for chromium(IV) oxide. Which is correct?

Accepted Answer

$$\mathrm{$$CrO_2$$}$$

Question 15

Which of the following best describes the process of oxidation in the formation of iron oxides?

Accepted Answer

Iron atoms lose electrons to oxygen atoms, forming ionic bonds.

Question 16

Which of the following is a real-world application of chromium(III) oxide?

Accepted Answer

It is used as a green pigment in paints and ceramics.

Question 17

A sample of iron(III) oxide weighs 160 g. How many moles of $$\mathrm{Fe_2O_3}$$ are present? (Molar mass of $$\mathrm{Fe_2O_3} = 160 g/$$mol)

Accepted Answer

1 mole

Question 18

Which of the following is the correct formula for iron(II) oxide?

Accepted Answer

$$\mathrm{FeO}$$

Question 19

If 2 moles of chromium(III) oxide react with excess aluminum in a thermite reaction, how many moles of aluminum oxide are produced? (Reaction: $$\mathrm{Cr_2O_3 + 2Al \rightarrow 2Cr + Al_2O_3})$$

Accepted Answer

1 mole

Question 20

Which of the following is NOT a possible oxidation state for chromium in its oxides?

Accepted Answer

+5

Transition Metal Oxides: Nomenclature and Classification

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