•   Letter -  A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

•   Reverse Code - Z Y X W V U T S R Q P O N M L K J I H G F E D C B A

•   Correct code for LUCKNOW is OFXPMLD.

•   English alphabats: ABCD EFGH IJKL MNOP QRST UVWX YZ

•   As per question: DCBA HGFE LKJI PONM TSRQ XWVU ZY

•   13th letter is P. And the 4th letter to its right is T.

Directions for the following 4 (four) items:

The correct answer is b: BIDNHTSSX.
To solve this problem, we need to understand the pattern used to encode the word 'MATHEMATICS' into 'LBSIDNZUHDR'. Let's break it down step by step:
     ● Step 1: Analyze the Pattern  
       We need to compare each letter of 'MATHEMATICS' with 'LBSIDNZUHDR' to find the pattern or rule applied.
           ○ M -> L
           ○ A -> B
           ○ T -> S
           ○ H -> I
           ○ E -> D
           ○ M -> N
           ○ A -> Z
           ○ T -> U
           ○ I -> H
           ○ C -> D
           ○ S -> R
     ● Step 2: Identify the Transformation  
       By observing the transformation, we can see that each letter in 'MATHEMATICS' is shifted by a certain number of positions in the alphabet to get the corresponding letter in 'LBSIDNZUHDR'. Specifically:
           ○ M (13) -> L (12): Shift of -1
           ○ A (1) -> B (2): Shift of +1
           ○ T (20) -> S (19): Shift of -1
           ○ H (8) -> I (9): Shift of +1
           ○ E (5) -> D (4): Shift of -1
           ○ M (13) -> N (14): Shift of +1
           ○ A (1) -> Z (26): Shift of -1
           ○ T (20) -> U (21): Shift of +1
           ○ I (9) -> H (8): Shift of -1
           ○ C (3) -> D (4): Shift of +1
           ○ S (19) -> R (18): Shift of -1
       The pattern alternates between shifting by -1 and +1.
     ● Step 3: Apply the Pattern to 'CHEMISTRY'  
       Now, apply the same pattern to encode 'CHEMISTRY':
           ○ C (3) -> B (2): Shift of -1
           ○ H (8) -> I (9): Shift of +1
           ○ E (5) -> D (4): Shift of -1
           ○ M (13) -> N (14): Shift of +1
           ○ I (9) -> H (8): Shift of -1
           ○ S (19) -> T (20): Shift of +1
           ○ T (20) -> S (19): Shift of -1
           ○ R (18) -> S (19): Shift of +1
           ○ Y (25) -> X (24): Shift of -1
       Therefore, 'CHEMISTRY' is encoded as 'BIDNHTSSX'.
     Thus, the correct answer is b: BIDNHTSSX.

When alphabets are numbered, then:

GHI = 789, DEF = 456, ABC = 123

According to the question,

GHI = 1578 = 789 × 2

DEF = 912 = 456 × 2 

ABC = 123 × 2 = 246

•  If we will write the English alphabet as described in the question we will get the 26 letters as –  AbCdEfGhIjKlMnOpQrStUvWxYz

•  So, July will be written jUlY.

•  After changing the expression as per the conditions given in the question, we get 10#5@1$5 = 10 - 5 × 1 ÷ 5.

•  Using BODMAS, we first get 1 / 5 = 1/5. Then we get 5 x 1/5 = 1. Then we get 10 – 1 = 9. Hence, we have answer 9.

•   Code is a letter back for first letter, two back for second letter, three back for the third letter, and so on.

•   So, correct code for DELHI is CCIDD.

•   RAMON → 12345

•   DINESH → 675849

•   H → 9, A → 2, M → 3

•   So HAMAM → 92323.

•   Since 2 is in ‘red colour chalk’, so it must mean something from this set. So 2 does not mean white.

•   Similarly 5 is in ‘red colour chalk’ so it couldn’t mean white.

•   Now 8 isn’t in ‘white colour chalk’ so 8 can’t mean white. So only remaining possibility is option (b).

•   In given code, first half of the word and second half of the word are reversed.

•   FRACTION will be written as CARFNOIT.