A compound is formed by two elements P and Q. The element Q forms ccp and atoms of element P occupy half of tetrahedral voids. What is the formula of the compound?
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → \(PQ\)
In a close packed (ccp) arrangement of N atoms, the number of tetrahedral voids is 2N and of octahedral voids N.
\( \displaystyle \text{Atoms of Q} = N,\qquad \text{tetrahedral voids} = 2N \)
\( \displaystyle \text{Atoms of P} = \frac{1}{2} \times 2N = N \)
\( \displaystyle \text{P : Q} = N : N = 1 : 1 \)
So the formula is PQ (the zinc blende, ZnS, arrangement).
Note: This question is from the pre-rationalised NCERT book (2022-23). The topic is not there in the latest NCERT book (2026-27), and it is also out of the CUET 2026 syllabus.