A) Which of the following equations shows a chemical change? (1 point)

Question

C3H8 + 5O2 → 3CO2 + 4H2O
H2O(s) → H2O(g)
C OH(l) → OH(g) 2H5 C2H5
NH3(g) → NH3(l)
A)
How many atoms of carbon (C) are present in the reactants of the following chemical
equation?
(1 point)
C7H16 + O2 → CO2 + H2O
1 atom
16 atoms
23 atoms
7 atoms

Answer 1

A) The equation that shows a chemical change is:
C3H8 + 5O2 → 3CO2 + 4H2O.
This equation represents the combustion of propane (C3H8), which is a chemical reaction where chemical bonds are broken and new substances are formed.

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B) In the reaction:
C7H16 + O2 → CO2 + H2O,
the number of carbon (C) atoms present in the reactants is 7 atoms.
This is because C7H16 contains 7 carbon atoms.