Question

1. which of these is not named correctly?

a. monocarbon dioxide, co₂
c. carbon monoxide, co
b. carbon dioxide, co₂
d. carbon trioxide, co₃

1. what is the formula for dihydrogen monoxide?

a. dmho
c. h₂o
b. o₂h
d. oh₂

1. which of the following is the formula for nitrogen trihydride?

a. nh
c. nh₃
b. n₃h
d. hn₃

Explanation:

16.

• For binary covalent compounds, the prefixes indicate the number of atoms.
• In option a, the correct name for \(CO_2\) is carbon dioxide (not monocarbon dioxide). The prefix “mono -” is not used for the first element when there is only one atom of it.
• Option b: \(CO_2\) is carbon dioxide (correct, as “di -” for two oxygen atoms).
• Option c: \(CO\) is carbon monoxide (correct, “mono -” for one oxygen atom).
• Option d: \(CO_3\) (if it were a stable compound, which it's not in the common sense here, but following naming rules) would be carbon trioxide (prefix “tri -” for three oxygen atoms).

• “Dihydrogen” means two hydrogen atoms (\(H_2\)) and “monoxide” means one oxygen atom (\(O\)).
• The formula for a compound is written with the more electropositive element (hydrogen here) first. So the formula is \(H_2O\).
• Option a: \(DMHO\) is not a valid chemical formula notation.
• Option b: \(O_2H\) has the elements in the wrong order (oxygen is more electronegative than hydrogen and should be second).
• Option d: \(OH_2\) also has the elements in the wrong order.

• “Nitrogen trihydride” means one nitrogen atom (\(N\)) and three hydrogen atoms (\(H_3\)).
• The formula is written with the less electronegative element (nitrogen) first.
• Option a: \(NH\) has only one hydrogen atom (should be three for “tri -”).
• Option b: \(N_3H\) has the wrong number of nitrogen atoms (should be one).
• Option d: \(HN_3\) has the elements in the wrong order (nitrogen should be first as it is less electronegative than hydrogen in this context).

Answer:

A. Monocarbon dioxide, \(CO_2\)

17.