Compound formulae depend on element valencies from periodic table groups Steps:

• Identify the groups of elements W, X, Y, Z from the periodic table diagram to determine their valencies.
• Match valencies to form neutral compound formulae (e.g., group 1 + group 17 = 1:1 ratio).
• Check each option's pairs against possible compounds.
• Select the option where both formulae balance valencies correctly. Not enough information: The periodic table diagram showing positions of W, X, Y, Z is missing, so valencies cannot be determined to verify any formulae. Why B is correct: Not enough information. Why the others are wrong:
• A: Not enough information.
• C: Not enough information.
• D: Not enough information.

Final answer: B