RRB NTPC Previous Year Paper 05 — Kerala PSC PYQ Practice with Answers

Correct answer (Option B):\nWhen we unscramble the letters of each option, they form words belonging to a specific category:\nOption A: LOWELY → YELLOW (A color)\nOption B: IFER → FIRE (A destructive burning/phenomenon)\nOption C: THIWE → WHITE (A color)\nOption D: WRONB → BROWN (A color)\n\nSince Yellow, White, and Brown are all names of colors, the word 'FIRE' does not belong to the group.\nOption B is correct.\n\nWhy others are wrong:\nOptions A, C, and D are incorrect choices because their rearranged words represent distinct colors, forming a consistent group from which Option B stands apart.\n\nStudy tip:\nIn word-based classification questions, always write down the rearranged words explicitly. Look for common categories such as colors, elements, animals, or occupations to find the odd one out.

Correct answer (Option B):\nFormula: Mean = (Sum of all observations) / (Total number of observations)\n\nGiven:\nObservations = 18, 16, 22, 13, ?\nTotal count = 5\nMean = 16\n\nStep 1: Express the mean equation\n16 = (18 + 16 + 22 + 13 + ?) / 5\n\nStep 2: Simplify the sum of known numbers\n18 + 16 + 22 + 13 = 69\n16 = (69 + ?) / 5\n\nStep 3: Cross-multiply to solve for ?\n16 × 5 = 69 + ?\n80 = 69 + ?\n? = 80 - 69\n? = 11\n\nOption B is correct.\n\nWhy others are wrong:\nOption A (9) is wrong because it results in a sum of 78 and a mean of 15.6.\nOption C (10) is wrong because it yields a mean of 15.8.\nOption D (12) is wrong because it leads to a total sum of 81 and a mean of 16.2.\n\nStudy tip:\nMean is simply the average of a distribution. For missing value problems, multiplying the mean by the total number of items gives the target total sum directly, making calculations faster.

Correct answer (Option A):\nLet us analyze the alphabetical shifts for each position in the pairs:\n\nFirst Letter Pattern:\nA → B (+1)\nB → C (+1)\nC → D (+1)\nD → E (+1)\n\nSecond Letter Pattern:\nN → O (+1)\nO → P (+1)\nP → Q (+1)\nQ → R (+1) — Wait, checking standard alphabet series:\nN(14), O(15), P(16), Q(17), so the next element must be R(18). Thus, following the standard (+1, +1) pattern sequentially, the next pair is ER. Let us verify option matching: Option D is ER.\n\nLet's re-verify the question options: (a) ES, (b) RE, (c) FS, (d) ER.\nApplying the +1 increment to both terms gives:\nD + 1 = E\nQ + 1 = R\nResulting in ER, which matches Option D.\nOption D is correct.\n\nWhy others are wrong:\nOption A (ES) incorrectly increments the second letter by +2 instead of +1.\nOption B (RE) reverses the correct sequence of the letters.\nOption C (FS) miscalculates both letters by skipping positions ahead.\n\nStudy tip:\nWhen working with letter series, write down the corresponding numerical positional values (A=1, B=2, ..., Z=26) to systematically track index changes without errors.

Correct answer (Option C):\nMars is universally designated as the 'Red Planet' due to the extensive presence of iron oxide (rust) on its surface, which gives it a distinctive reddish, fiery appearance visible from Earth.\nOption C is correct.\n\nWhy others are wrong:\nOptions A and B (Morning Star / Evening Star) refer to Venus because of its exceptional brightness at dawn and dusk.\nOption D (Blue Planet) refers to Earth due to its abundant surface liquid water.\n\nRemember:\nMars has two small moons, Phobos and Deimos, and contains Olympus Mons, the largest known volcano in our solar system.

Correct answer (Option A):\nThe common name for a saturated aqueous solution of calcium hydroxide, represented chemically as Ca(OH)₂, is lime water. It is a clear liquid that turns milky when carbon dioxide gas is passed through it due to the formation of insoluble calcium carbonate precipitate.\nOption A is correct.\n\nWhy others are wrong:\nOption B (Diet soda) is a carbonated beverage containing artificial sweeteners.\nOption C (Salt solution) usually implies sodium chloride dissolved in water.\nOption D (Vinegar) is a dilute solution of acetic acid (CH₃COOH).\n\nRemember:\nCalcium hydroxide is also used in white-washing and is produced by reacting quicklime (calcium oxide, CaO) with water, an exothermic process known as slaking of lime.