CTET Paper II (Mathematics and Science) 4 Jan 2022 Solved Paper

Concept:We verify each statement logically. Only one holds true for all cases.Explanation:Check Option A: $\sqrt{0.9} = \sqrt{9/10} = 3/\sqrt{10} \neq 0.3$. So false.Check Option B: For integer a, $a^3$ is not always greater than $a^2$. Example: $a = -2$ gives $(-2)^2 = 4$, $(-2)^3 = -8$, so $4 > -8$. False.Check Option C: If $a^2$ ends in 9, a could end in 3 or 7. For a=7, $a^2=49$ ends in 9, but $a^3=343$ ends in 3, not 7. False.Check Option D: If a divides b, then b = a·k for some integer k. Then $b^3 = a^3·k^3$, so $a^3$ divides $b^3$. True.Answer:Option D is the true statement.