Question

Fill in the blanks:
$FeS + {H_2}S{O_4} \to FeS{O_4} +$
\\_\\_\\_\\_ + \\_\\_\\_\\_ \to NaCl + {H_2}O
KOH + {H_2}S{O_4} \to \\_\\_\\_\\_ + {H_2}O
$2Na + 2{H_2}O \to$
$HgC{l_2} + Hg \to$
Ca{(OH)_2} + \\_\\_\\_\\_ \to \\_\\_\\_\\_ + \\_\\_\\_\\_
2FeS{O_4}\xrightarrow{{heat}}F{e_2}{O_3} + \\_\\_\\_\\_ + \\_\\_\\_\\_

Answer 1

These reactions are examples of displacement reactions, redox reactions or neutralization reactions. In redox reactions the change of oxidation state takes place of the elements on moving from reactant to product side.

Complete step by step answer: Let us evaluate and determine the blank reagents or the products of the given reactions.
$FeS + {H_2}S{O_4} \to FeS{O_4} + {H_2}S$
Iron sulfide on treatment with sulfuric acid undergoes a double displacement reaction to produce iron sulfate and hydrogen sulfide. In double displacement reactions the components on the reactant side are replaced in the product side. The cations and the anions of the reactant are interchanged in the products.
$NaOH + HCl \to NaCl + {H_2}O$
This is an example of a neutralization reaction. When an acid is treated with a base, salt and water are formed. Here $NaCl$ is the salt produced by the neutralization of an acid which is $HCl$ and a base which is$NaOH$ .
$KOH + {H_2}S{O_4} \to {K_2}S{O_4} + {H_2}O$
This is also a neutralization reaction. $KOH$ is the base and ${H_2}S{O_4}$ is the acid used in this reaction. Both the reactants undergo reaction to produce a salt ${K_2}S{O_4}$ and water.
$\;2Na + 2{H_2}O \to 2NaOH + {H_2}$
It is a displacement reaction as the more reactive element sodium displaces the less reactive element i.e. hydrogen. Alkali metals are very electropositive in nature and are very reactive.
$HgC{l_2} + Hg \to H{g_2}C{l_2}$
It is an example of a redox reaction. Here $HgC{l_2}$ acts as an oxidizing agent and $Hg$ is the reducing agent.
$Ca{\left( {OH} \right)_2} + HCl \to CaC{l_2} + {H_2}O$
This is also a neutralization reaction. $Ca{\left( {OH} \right)_2}$ is the base and $HCl$ is the acid used in this reaction. Both the reactants undergo reaction to produce a salt $CaC{l_2}$ and water.
$2FeS{O_4}\xrightarrow{{heat}}F{e_2}{O_3} + S{O_2} + S{O_3}$
It is an example of a redox reaction. Here $Fe$ is the oxidizing agent and $S$ is getting reduced.

Note: All the chemical reactions written are balanced chemical reactions. The number of elements present in the reactant side and product are equal. The law of conservation of mass is also satisfied in all the equations.