CTET Paper I (Classes I to V) 8 Jan 2022 Solved Paper

Concept:A perfect cube is a number that can be expressed as an integer raised to the power 3.Explanation:Check each option by prime factorisation.25 = $5 \times 5 = 5^2$ — exponent 2 is not a multiple of 3.36 = $2^2 \times 3^2$ — exponents 2 and 2 are not multiples of 3.64 = $2 \times 2 \times 2 \times 2 \times 2 \times 2 = 2^6$ — exponent 6 is a multiple of 3, so 64 = $(2^2)^3 = 4^3$.81 = $3^4$ — exponent 4 is not a multiple of 3.Thus only 64 is a perfect cube.Answer:C. 64