Question

When zinc reacts with dilute hydrochloric acid, the gas evolved is:
A.Hydrogen
B.Chlorine
C.Hydrogen chloride
D.None of these

Answer 1

The given problem is a characteristic reaction for the acids, it is a reaction of the substitution type. To find the answer we just have to substitute the given metal with the element which is attached to the non-metallic compound and then we will get the answer in the form of the compound other than the metal chloride left.

Complete step by step answer:
Firstly we have to sort out that what kind of the reaction will take place in the reaction above :
According to the principle that whenever the metal reacts with the hydrochloric acid then the substitution reaction will take place. This will happen due to the ionic nature of the $HCl$ , as the ionic bond suggests that the bond in which there is more difference in the electronegativity of the reacting elements will be much more stable than the ones with the least difference.
All the metals are more electropositive than the Hydrogen atom. That is why they can easily displace it in the process of the bonding thereby performing the substitution and then forming the compound.
Now in the given problem we know that the given metal is a transitionals metal of Zinc $Zn$ so there will be a substitution where the zinc will displace the hydrogen atom and then form the zinc chloride in the process and liberate the hydrogen.
$Zn + 2HCl \to ZnC{l_2} + {H_2}$

So the right option is the option A, hydrogen.

Note: A substitution reaction is also called as the single displacement reaction or the single substitution reaction. It is an important chemical reaction, in which one functional group ( could be any ) in a chemical compound is replaced or substituted by another functional group. Substitution reactions are also of prime importance in the field of organic chemistry.