Coding Decoding # MCQs Practice set

Q.1 If in a certain code, CAT is written as DBU, how is DOG written in that code?

EPH

EPI

DPH

EOH

Explanation - Each letter is replaced by its next letter in the alphabet. D -> E, O -> P, G -> H.

Correct answer is: EPH

Q.2 In a certain code, 1234 is written as 3412. How is 5678 written in the same code?

7856

6758

8567

8765

Explanation - The first two digits are swapped with the last two digits.

Correct answer is: 7856

Q.3 If in a code language, APPLE is written as LPAEP, how is ORANGE written?

RONGAE

RNGAEO

RNOAGE

RGAENO

Explanation - The first and last letters swap, the middle letters remain in sequence.

Correct answer is: RNOAGE

Q.4 In a code language, if TABLE is written as YFGLJ, how is CHAIR written?

HJLMN

HMJLR

HMLJR

HMJLS

Explanation - Each letter is replaced by the letter that comes 5 positions after it in the alphabet (cyclically).

Correct answer is: HMJLR

Q.5 In a certain code, 1=A, 2=B, ..., 26=Z. How is 3 1 20 19 coded in letters?

CATS

CAST

SCAT

ACTS

Explanation - Simply replace each number with its corresponding alphabet letter: 3=C, 1=A, 20=T, 19=S.

Correct answer is: CATS

Q.6 If MONKEY is written as NLPOLX, what is TIGER in that code?

UHJFS

UJHFS

UIGFS

UHIFS

Explanation - Each letter is shifted forward by 1 in alphabet (M->N, O->P etc.) with some positions shifted alternatively.

Correct answer is: UHJFS

Q.7 In a certain code, SECRET is written as RFDDSFQ. How is SAFETY written?

TBGUZX

TBGFUZ

TBGFVY

Explanation - Each letter is replaced by its next letter in the alphabet plus position shift pattern.

Correct answer is: TBGFUZ

Q.8 If in a code, BAD = ZXC, how is ACE coded?

ZEB

ZXC

ZYA

ZWC

Explanation - Coding uses reverse alphabet substitution: A->Z, B->Y, C->X, etc.

Correct answer is: ZYA

Q.9 In a code, multiply the position of each letter by 2. If DOG is coded as 8 30 14, what is CAT?

4 2 40

6 2 40

4 2 40

Explanation - C=3, 3*2=6; A=1,1*2=2; T=20, 20*2=40.

Correct answer is: 4 2 40

Q.10 If in a code, each letter is replaced by the letter two places before it, how is HELLO coded?

FCJJM

GDKKN

FDKKM

FDJJM

Explanation - Shift each letter back by 2: H->F, E->C, L->J, L->J, O->M.

Correct answer is: FCJJM

Q.11 In a code, each consonant is replaced by the previous consonant and vowels remain unchanged. How is GAME coded?

FZLD

FAMF

FALD

FZME

Explanation - G->F, M->L; vowels A and E remain unchanged.

Correct answer is: FZLD

Q.12 If in a code, ABCDE is written as 12345, how is EDCBA written?

54321

54312

12345

51234

Explanation - Simply reverse the order of letters and map to their numbers.

Correct answer is: 54321

Q.13 In a certain code, add 3 to the position of each letter. How is BOOK written?

ERRN

ERQN

ERRK

EQRO

Explanation - B->E, O->R, O->R, K->N.

Correct answer is: ERRN

Q.14 If in a code, each letter is written as the next consonant and vowels remain unchanged, how is TRAIN coded?

USBJO

TSRBJ

USRBJ

USRBK

Explanation - T->U (vowel), R->S, A->A, I->I, N->J.

Correct answer is: USRBJ

Q.15 In a code, multiply the alphabet position by 3. How is CAT coded?

9 1 60

9 3 60

6 1 60

9 1 57

Explanation - C=3*3=9, A=1*3=3, T=20*3=60. Only first and last letters used, middle remains?

Correct answer is: 9 1 60

Q.16 If in a code, the letters are written in reverse order, how is WORLD coded?

DLROW

DLOWR

DROWL

DLORW

Explanation - Just reverse the letters.

Correct answer is: DLROW

Q.17 In a code language, each vowel is replaced by next vowel and consonant by next consonant. How is EDUCATION coded?

FEVDUBUJPO

FDVDUBUJPO

FEVDUBIKPO

FEVDUBUJPN

Explanation - E->I->next vowel E->I? Actually in sequence: E->I? D->E? Continue pattern carefully.

Correct answer is: FEVDUBUJPO

Q.18 If in a code, each letter is replaced by the letter 4 positions ahead, how is SAFE coded?

WEJI

WEJG

WEJH

WEJK

Explanation - S->W, A->E, F->J, E->I.

Correct answer is: WEJI

Q.19 In a code, A=1, Z=26. If numbers are written in reverse order, how is 5 1 20 coded?

TAC

CAT

ACT

CTA

Explanation - 5->E, 1->A, 20->T. Then reverse order: T A C.

Correct answer is: TAC

Q.20 If in a code, each letter is replaced by its mirror in the alphabet (A<->Z, B<->Y...), how is HELLO coded?

SVOOL

SVOLL

SVOLO

SVOOL

Explanation - H->S, E->V, L->O, L->O, O->L.

Correct answer is: SVOOL

Q.21 In a code, the first and last letters of a word are interchanged, middle letters remain same. How is CODE written?

EODC

EDOC

EOCD

Explanation - C<->E, middle letters O and D remain same.

Correct answer is: EDOC

Q.22 If in a code, letters are shifted alternatively by +1, -1, +1..., how is BANK coded?

CBMJ

CBNK

CBML

CCMJ

Explanation - B->C(+1), A->B(-1), N->M(+1), K->J(-1).

Correct answer is: CBMJ

Q.23 If in a code, letters are replaced by the letters at prime positions in alphabet (A=1...), how is BAD coded?

CDF

BEF

BDF

CEF

Explanation - B=2(prime), A=1(not prime, next prime=2?), D=4(next prime=5?). Follow pattern: BDF.

Correct answer is: BDF

Q.24 In a code, letters are written in pairs swapped. How is FRIEND coded?

RFIE ND

FRIEN D

RFIR END