Question

Question
1
Question
2
A)
Hydrogen (H
) and oxygen (O
) combine to make water (H
O) in the following equation.
6H
+ 3O
→ ?H
O
How many water molecules would be produced?
(1 point)
2
2
2
2
2
2
six
three
four
five
A)
In photosynthesis, carbon dioxide (CO
) and water (H
O) combine to form the sugar glucose (C
H
O
)in the following reaction:
6CO
+ 6H
O → C
H
O
+ ?
Assuming this equation is balanced, which part is missing from the product side?
(1 point)
2
2
6
12
6
2
2
6
12
6
6 carbon atoms
12 oxygen atoms
12 hydrogen atoms
6 oxygen atoms
Question
3
Question
4
A)
Which statement accurately describes what happens in a reaction when reactants become products?
(1 point)
Some reactants rearrange to form products, and any leftover reactants are lost.
Reactant compounds bond together to form bigger product compounds.
Atomic bonds break and form, constantly changing between the reactant and product compounds.
Reactant bonds break and atoms rearrange to form new product combinations.
A)
Methane (CH
) and oxygen (O
) combine to make carbon dioxide (CO
) and water (H
O) in thefollowing unbalanced equation.
CH
+ O
→ CO
+ H
O
How many oxygen molecules are necessary in order to complete this reaction?
(1 point)
4
2
2
2
4
2
2
2
two
three
four
one
Question
5
A)
Use the equation for the formation of water to answer the question.
2H
+ O
→ 2H
O
Elements such as oxygen and hydrogen naturally exist as diatomic molecules (i.e., in a paired-atomform). Does the equation for the formation of water violate the law of conservation of mass? Why or whynot?
(1 point)
2
2
2
Yes, it does because there are two oxygen atoms in the reactants and only one in the product.
No, it does not because the number and mass of atoms are conserved even though the number ofmolecules is not.
No, it does not because there are two water molecules, so the bonds within the diatomic molecules werenot broken.
Yes, it does because the diatomic oxygen molecule is not present on both sides of the equation.

Answer 1

Here are the answers with brief explanations:

1) 6 H + 3 O → ? H2O
Answer: three H2O molecules.
Reason: Each H2O needs 2 H and 1 O, so 6 H /2 = 3 and 3 O /1 = 3 → 3 water molecules.

2) 6 CO2 + 6 H2O → C6H12O6 + ?
Answer: 6 O2 (which is 12 oxygen atoms).
Reason: Photosynthesis balanced equation produces 6 O2 (12 O atoms) alongside C6H12O6.

3) Which describes what happens in a reaction?
Answer: Reactant bonds break and atoms rearrange to form new product combinations.
Reason: Chemical reactions involve breaking/forming bonds and rearranging atoms into new substances.

4) CH4 + O2 → CO2 + H2O (balance)
Answer: two O2 molecules.
Reason: Balanced: CH4 + 2 O2 → CO2 + 2 H2O (2 O2 supply the 4 oxygen atoms needed).

5) 2 H2 + O2 → 2 H2O — does this violate conservation of mass?
Answer: No — because the number and mass of atoms are conserved even though the number of molecules changes.
Reason: LHS and RHS have equal numbers of each atom (4 H and 2 O), so mass is conserved.