Question

The anionic sites occupied by unpaired electrons are called F-centers or colour centers. They impart ______$\left(X\right)$ colour to the crystals on $NaCl.$ Excess of lithium makes $LiCl$ crystals ______$\left(Y\right)$ and excess of potassium makes $KCl$ crystals ______$\left(Z\right)$. $\left(X\right)$, $\left(Y\right)$ and $\left(Z\right)$ are:

• A. yellow, green and pink respectively.
• B. pink, yellow and violet (or lilac) respectively.
• C. yellow, pink and violet (or lilac) respectively.
• D. red, yellow and pink respectively,

Answer 1

Answer: (C)

yellow, pink and violet (or lilac) respectively.

$NaCl$ shows the metal excess defect, which results in the formation of an F-center in the crystal. When light falls on this crystal, the electron in F-center gets excited. This F-center is then responsible for the yellow $\left(X\right)$ color of $NaCl$.

In a similar way, the excess of lithium imparts Pink $\left(Y\right)$ colour of $LiCl$ crystals.

In a similar way, the excess of potassium imparts violet/lilac $\left(Z\right)$ colour of $KCl$ crystals.

Hence, Option "C" is the correct answer.