Suppose 10 atoms of carbon (C) react with 20 atoms of oxygen (O) to form 10 molecules of carbon dioxide (CO2 ). According to the law of conservation of matter, how many atoms are present in this reaction?

Question

1. 30
2. 15
3. 20
4. 10

Answer 1

To find the total number of atoms present in the reaction, we can add the number of atoms of each element involved.

In the reaction:

• There are 10 atoms of carbon (C).
• There are 20 atoms of oxygen (O).

When carbon reacts with oxygen to form carbon dioxide (CO2), each molecule of CO2 contains 1 carbon atom and 2 oxygen atoms. In total, for the formation of 10 molecules of CO2, we would have:

• 10 carbon atoms (1 per molecule × 10 molecules)
• 20 oxygen atoms (2 per molecule × 10 molecules)

Now, let's add the total number of atoms:

• Total carbon atoms = 10
• Total oxygen atoms = 20
• Total atoms = 10 (C) + 20 (O) = 30 atoms

Thus, according to the law of conservation of matter, the total number of atoms present in this reaction is 30.

The correct answer is 1. 30.