Question

The compound $N{H_4}{C_2}{H_3}{O_2}$ is made up of how many elements$?$
A) One
B) Two
C) Three
D) Four

Answer 1

An element is simply a particular species of atom with one particular atomic number assigned to it hence occupying the same position in the periodic table. In the question ammonium acetate is given. You have to pick out how many unique elements are present in the given compound.

Complete step-by-step answer:
An element is a pure substance consisting only of atoms that all have the same numbers of protons in their atomic nuclei hence one particular atomic number assigned to it and occupying the same position in the periodic table. In the question, $N{H_4}{C_2}{H_3}{O_2}$ is given and we need to find out the different types of elements present in the compound.

Now, the different types of elements present in $N{H_4}{C_2}{H_3}{O_2}$ are:
$\bullet$Nitrogen $\left( N \right)$ having an atomic number $7$, present in the group $15$ of period $2$.
$\bullet$Hydrogen $\left( H \right)$ having an atomic number $1$, present in the group $1$ of period $1$.
$\bullet$Carbon $\left( C \right)$ having an atomic number $6$, present in the group $14$ of period $2$.
$\bullet$Oxygen $\left( O \right)$ having an atomic number $8$, present in the group $16$ of period $2$.
Hence the number of elements present in $N{H_4}{C_2}{H_3}{O_2}$ are four.

Additional Information:
Unlike chemical compounds, chemical elements cannot be broken down into simpler substances by any chemical means. When different elements undergo chemical reactions, atoms are rearranged into new compounds held together by chemical bonds. Only a minority of elements, such as silver and gold, are found that do not combine with other elements and exist as relatively pure native element minerals.

Hence the correct answer is option ‘D’.

Note: For these kinds of questions you must know the periodic table and the position of the different elements in the periodic table properly. If you know the different positions of the elements you will know that the elements have different atomic numbers and hence you can easily identify them in a given compound.