Explanation:
Medieval number one. There you havt it.
Answer:
Iron and Oxygen
Explanation:
Fe is Iron and O2 is Oxygen
Answer:

Explanation:
Hello!
In this case, we can divide the problem in two steps:
1. Dilution to 278 mL: here, the initial concentration and volume are 1.20 M and 52.0 mL respectively, and a final volume of 278 mL, it means that the moles remain the same so we can write:

So we solve for C2:

2. Now, since 111 mL of water is added, we compute the final volume, V3:

So, the final concentration of the 139 mL portion is:

Best regards!
CH4+2O2–>CO2+2H2O
4Fe+3O2–>2Fe2O3
Can not be D or B and A is not enough so C is right.