Question

Write down the formula of the compound formed between C and D.
A. $\text{CD}$
B. $\text{C}{{\text{D}}_{2}}$
C. $\text{C}{{\text{D}}_{4}}$
D. $\text{C}{{\text{D}}_{3}}$

Answer 1

Hint: The question is all about bond formation. The number of bonds formed by the element with another element depends on the valency of that element (especially elements which don’t have d-orbitals).

Complete answer:
Before dealing with the question, let us define what is valency, valency is the count of the maximum number of atoms that an element can lose or gain to achieve inert gas configuration (noble gas configuration). Carbon belongs to period 2 and have configuration as $2,4\text{ or 1}{{\text{s}}^{2}}\text{2}{{\text{s}}^{2}}\text{2}{{\text{p}}^{2}}$. So, the valency of carbon will be 4 as there are 4 valence electrons in it.

Now, talking about deuterium, it is an isotope of hydrogen with the number of protons as 1 and the number of electrons as 1. While forming bonds with other elements deuterium resembles hydrogen. It has the same valency as hydrogen which is 1.

So, the four valencies or vacancies on carbon atoms can be filled by four deuterium atoms. One electron from deuterium and one electron from the carbon atom will combine to form a bond. There are four valence electrons on carbon atoms. Thus, the structure formed will be

The molecular formula of this structure will be $\dfrac{\text{C}}{1}\searrow \dfrac{\text{D}}{4}\text{ and }\dfrac{\text{C}}{1}\nearrow \dfrac{\text{D}}{4}$, so, the chemical formula will be $\text{C}{{\text{D}}_{4}}$.

The correct answer to this question is the formula of compound formed between carbon and deuterium is$\text{C}{{\text{D}}_{4}}$, which is option ‘c’.

Note:
The compound that can also be formed by the reaction of and is ${{\text{C}}_{2}}{{\text{D}}_{2}}$ just like ${{\text{C}}_{2}}{{\text{H}}_{2}}$ (acetylene). The structure of ${{\text{C}}_{2}}{{\text{D}}_{2}}$ is