Carbon monoxide and carbon dioxide are both potentially dangerous compounds if inhaled in excess by people and animals. How do the two compounds compare in terms of chemical make-up?

A. Carbon monoxide has no oxygen and carbon dioxide has two oxygen.
Incorrect. Carbon dioxide does have two oxygen, but carbon monoxide has one oxygen.

B. Carbon monoxide has one oxygen and one oxygen, but carbon dioxide has two carbons and one oxygen.
Incorrect. Carbon dioxide has one carbon and one oxygen, but the prefix indicates the number of the element whose name it is connected to, so carbon dioxide has two oxygen atoms.

C. They both have oxygen and carbon in the same ratio.
Incorrect. Carbon monoxide has a ratio of 1:1 C:O, but carbon dioxide has a 1:2 ratio.

D. Carbon monoxide has less oxygen than carbon dioxide but the same number of carbons.
Correct! The formulas are CO and CO₂ respectively.

Disulfur decafluoride is a gas discovered in 1934 by Denbigh and Whytlaw-Gray. It is highly toxic and was considered a potential chemical warfare pulmonary agent in World War II because it does not produce lacrimation or skin irritation, thus providing little warning of exposure. What is the chemical formula of disulfur decafluoride?

A. SF
Incorrect. Look at the prefixes to determine the correct number of each element in the compound.

B. S₂F₁₀
Correct! This would be the correct formula for disulfur decafluoride.

C. S₂F₅
Incorrect. Penta is the prefix for 5.

D. S₁₀F₂
Incorrect. The prefix does not switch to the other element; it indicates the number for the element it is attached to.

Nitrogen and fluorine can bond in multiple ways making different compounds. Two common compounds are NF₃ and N₂F₄. What are their respective names?

A. Mononitrogen trifluoride and mononitrogen tetrafluoride
Incorrect. Mono is never used on the first element's name.

B. Nitrogen trifluorine and dinitrogen tetrafluorine
Incorrect. Compounds must end in –ide.

C. Nitrogen trifluoride and dinitrogen tetraflouride
Correct! These are the correct names for NF₃ and N₂F₄.

D. Both are nitrogen fluoride.
Incorrect. You must use prefixes to tell how many of each element.

What is the name of the compound P₄S₅?

A. Phosphorus(II) sulfide
Incorrect. Roman numerals are used only for ionic compounds containing transition metals.

B. Tetraphosphorus pentasulfide
Correct! Tetraphosphorus pentasulfide is the correct name for P₄S₅.

C. Tetraphospide pentasulfate
Incorrect. The wrong suffixes are used.

D. Phosphorus sulfide
Incorrect. Use the correct prefixes.