A chemical reaction is the process in which atoms present in the starting substances rearrange to give new chemical combinations present in the substances formed by the reaction. These starting substances of a chemical reaction are called the reactants, and the new substances that result are called the products.
The reaction gives out a yellow showery sparks and produces a black solid. Iron reacts with dilute hydrocloric acid to give iron chloride and hydrogen gas.
2Fe+2Hcl3 = 2FeCl3+H2
Answer:

Explanation:
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In this case, since calcium's oxidation state when forming ionic bonds is +2 and sulfur's oxidation state when bonding those bonds is -2, for the required formula we write:

Now, since they have the same charge number, we infer the ionic compound formed when they bond is calcium sulfide:

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I think it's A but it might be different from your school and mine