In a code language 'MATHEMATICS' is written as 'LBSIDNZUHDR'. How is 'CHEMISTRY' written in that code language ?
- (a) DIDLHRSSX
- (b) BIDNHTSSX ✓ UPSC's answer
- (c) BIDLHTSSX
- (d) DGFLIRUQZ
Why the answer is (b)
• MATHEMATICS → LBSIDNZUHDR: the letters are shifted alternately −1 and +1 (M→L, A→B, T→S, H→I, E→D, M→N, …).
• Apply the same to CHEMISTRY: C→B, H→I, E→D, M→N, I→H, S→T, T→S, R→S, Y→X.
• CHEMISTRY is written BIDNHTSSX — option (b).
Why the other options are wrong
- (a) DIDLHRSSX
- DIDLHRSSX starts with +1 (C→D) instead of −1 and shifts M to L instead of N.
- (c) BIDLHTSSX
- BIDLHTSSX shifts M (4th letter) to L, but the 4th letter should move +1 to N.
- (d) DGFLIRUQZ
- DGFLIRUQZ applies the shifts the other way round (+1 first) and leaves I unchanged, so it does not follow the code.
Asked in the CSAT Paper II of the UPSC Civil Services Preliminary Examination 2021, held on 10 October 2021. Question and answer key: Union Public Service Commission. Explanation: UPSC Answer Check.