Question

What is obtained when ammonium dichromate is heated?
A.Nitrogen
B.Oxygen
C.Ammonia
D.None of the above.

Answer 1

Reagents: those compounds which react with each other to form the other compounds, are known as reagents. They are present on the left side of the reaction.
Products: The compounds formed by the reaction of reagents, are known as products. They are present on the right side of the reaction.

Complete step by step solution:
First of all we will talk about reagents and products.
Reagents: those compounds which react with each other to form the other compounds, are known as reagents. They are present on the left side of the reaction.
Products: The compounds formed by the reaction of reagents, are known as products. They are present on the right side of the reaction.
Balanced reaction: The reaction in which the number of all atoms on both sides i.e. on the reactant side and on the product side are same, are known as balanced reactions.
Limiting reagent: The reagent which is completely consumed during the reaction, is known as limiting reagent.
Excess reagent: The reagent which is left after the reaction, is known as excess reagent.
Oxidation number: It is also known as oxidation state. It is defined as the number of electrons which are gained or loss of an atom or ion to form a molecule, is known as oxidation number. Oxidation number of any element is calculated as the sum of the oxidation number of all atoms present in the molecule is equal to zero in case of neutral molecule or the given charge in case of ion.
Ammonium dichromate: It is the compound formed of ammonia and chromate. And chromate has oxidation number $+ 6$ in this molecule.
Now we have to write the equation when ammonium dichromate is heated. The reaction is as follows: ${{\text{(N}}{{\text{H}}_{\text{4}}}{\text{)}}_{\text{2}}}{\text{C}}{{\text{r}}_{\text{2}}}{{\text{O}}_{\text{7}}}\xrightarrow{\Delta }{{\text{N}}_{\text{2}}}{\text{ + 4}}{{\text{H}}_{\text{2}}}{\text{O + C}}{{\text{r}}_{\text{2}}}{{\text{O}}_{\text{3}}}$
From the balanced chemical reaction of ammonium dichromate on heating we can determine that ammonium dichromate produces nitrogen gas on heating.

Hence option A is correct.

Note: Transition elements: The elements which are in group three to twelve. They can show different valencies by donating the electrons from $s$ and $d$ block electrons. And also they form complex compounds because of the presence of $d -$ electrons.