I think the answer might be nuclear physics
Answer:
4.5 kilograms of silicon dioxide is required to produce 3.00 kg of SiC.
Explanation:
The balanced equation for the reaction between silicon dioxide and carbon at high temperature is given as:

1 mole silicon dioxide reacts with 3 moles of carbon to give 1 moles of silicon carbide and 2 moles of carbon monoxide.
Mass of SiC = 3.00kg = 3000.00 g
1 kg = 1000 g
Molecular mass of SiC = 40 g/mol
Moles of SiC = 
According to reaction, 1 mole of SiC is produced from 1 mole of silicon dioxide.
Then 75 moles of SiC will be produce from:
of silicon dioxide.
mass of 75 moles of silicon dioxde:

4.5 kilograms of silicon dioxide is required to produce 3.00 kg of SiC.
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Answer:
If the half-life of 14C is 5730 years, when this period of time has passed it will have been halved, it is called the exponential decay law of radioactive isotopes.
Answer:
If there is 0.66 moles of iron(III)oxide produced, there reacte 0.99 moles of oxygen (O2)
Explanation:
Step 1: Data given
Number of moles iron (III) oxide (Fe2O3) = 0.66 moles
Step 2: The balanced equation
4Fe + 3O2 → 2Fe2O3
Step 3: Calculate moles of oxygen (O2)
For 4 moles Fe consumed, we need 3 moles of O2 to produce 2 moles of Fe2O3
For 0.66 moles Fe2O3 produced, we need 3/2 * 0.66 = 0.99 moles of O2
If there is 0.66 moles of iron(III)oxide produced, there reacte 0.99 moles of oxygen (O2)