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Answer:
D) Adding a catalyst
Explanation:
Adding a catalyst decreases activation energy and allows the reaction to occur more easily.
The given balanced reaction is,

The stoichiometric coefficients of each element or compound represents the number of moles of that element or compound required for the complete reaction to take place.
The mole ratios of different products and reactants will be:



So the mole ratio comparing iron (Fe) and oxygen gas (
) is
4 : 3
Answer:
A scientific problem is something you don't understand but you can do an experiment to help you understand. Scientific problems are usually based on observation of scientific phenomena. Here is some advice to help you identify a scientific problem you can address by designing your own experiment.
Explanation:
Example of a scientific problem are Clean Drinking Water.