Question

multiple choice
read each question carefully and circle the correct answer.

1. what does the \h\ stand for in the formula h₂o?

a. helium
b. hydrogen
c. oxygen
d. carbon

1. how many oxygen atoms are in a molecule of h₂o?

a. 1
b. 2
c. 3
d. 4

1. what does the number after a chemical symbol represent?

a. the type of element
b. the number of molecules
c. the number of atoms of that element
d. the number of electrons

1. how many total oxygen atoms are in 3co₂?

a. 1
b. 2
c. 6
d. 9

1. in the formula 2h₂o, how many hydrogen atoms are there in total?

a. 2
b. 4
c. 6
d. 8

Explanation:

1. In chemical formulas, elements are represented by their symbols. Hydrogen's symbol is "H".
2. In the formula \(H_2O\), the sub - script after the element symbol indicates the number of atoms. For oxygen (\(O\)) in \(H_2O\), there is no sub - script, which implies 1 atom.
3. By definition, the number after a chemical symbol in a formula represents the number of atoms of that element.
4. In \(CO_2\), there are 2 oxygen atoms. For \(3CO_2\), we multiply the number of oxygen atoms in one \(CO_2\) molecule by 3. So \(2\times3 = 6\).
5. In \(H_2O\), there are 2 hydrogen atoms. For \(2H_2O\), we multiply the number of hydrogen atoms in one \(H_2O\) molecule by 2. So \(2\times2=4\).

Answer:

1. B. Hydrogen
2. A. 1
3. C. The number of atoms of that element
4. C. 6
5. B. 4