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CBSE Class 10 Maths Chapter 1 Real Numbers Model Questions - 5 Marks - Part 1
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CBSE Class 10 Maths Chapter 1 Real Numbers Model Questions - 5 Marks - Part 1

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Portal ID: DMA-EXAM-2026 Security: Encrypted Status: Active Examination

SECTION E — Long Answer Type Questions [5 Marks Each]

    Q1. Find the HCF of $408$ and $1032$. Express it in the form $1032p - 408 \times 5$ and hence find the value of $p$.
    Q2. If $m$ and $n$ are odd positive integers, prove that $m^2 + n^2$ is even, but not divisible by $4$.
    Q3. Let $p$ be a prime number. Prove that $\sqrt{p} + \sqrt{p+2}$ is always an irrational number.
    Q4. If $p$ is a prime number, prove that $\sqrt{p}$ is irrational.
    Q5. Prove that $\frac{1}{\sqrt{5}}$ is irrational.
    Q6. Prove that for any positive integer $x$, $x^3 - x$ is divisible by $6$. (Hint: Factorize into consecutive integers and apply prime breakdown).
    Q7. The HCF of two numbers $a$ and $b$ is $12$ and their product is $6340$. If the ratio of their prime powers allows up to two distinct common factors, determine all possible values of $(a, b)$.
    Q8. Prove that $\frac{3}{2\sqrt{5}}$ is irrational.
    Q9. Prove that $\sqrt{p} + \sqrt{q}$ is irrational, where $p$ and $q$ are distinct prime numbers.
    Q10. Show that for any positive integer $n$, $\sqrt{n}$ is either a rational or an irrational number.
    Q11. Two tankers contain 850 liters and 680 liters of petrol respectively. Find the maximum capacity of a container which can measure the petrol of either tanker in exact number of times.
    Q12. Let $\beta$ and $\delta$ be positive integers. The HCF of $\beta$ and $630$ is $210$, and the HCF of $\delta$ and $110$ is $55$. Find the maximum possible value of the HCF of $(\beta, 630, \delta, 110)$ using step-by-step Euclid's division algorithm logic.
    Q13. Show that any number of the form $4^n$, where $n$ is a natural number, can never end with the digit zero.
    Q14. If $x = \frac{3 + \sqrt{5}}{2}$ and $y = \frac{3 - \sqrt{5}}{2}$, show that $x^3 + y^3$ is a rational number, whereas $x^3 - y^3$ is an irrational number. Find their exact values.
    Q15. Find the largest number that divides 2053 and 967 and leaves a remainder of 5 and 7 respectively.
    Q16. Three sets of English, Mathematics, and Science books containing 336, 240, and 96 books respectively have to be stacked in such a way that all the books are stored subject-wise and the height of each stack is the same. Find the number of stacks.
    Q17. Prove that the product of three consecutive positive integers is divisible by 6.
    Q18. Find the smallest number which when increased by 17 is exactly divisible by 520 and 468.
    Q19. Two positive integers $a$ and $b$ are expressible in the form $a = p \cdot q^2$ and $b = p^3 \cdot q$, where $p$ and $q$ are prime numbers. If $\text{LCM}(a, b) = p^3 q^3$ and $\text{HCF}(a, b) = p \cdot q$, verify whether $\text{HCF}(a, b) \times \text{LCM}(a, b) = a \times b$ holds true, and find the smallest natural number $n$ for which $(pq)^n$ ends with zero.
    Q20. A merchant has 120 liters of oil of one kind, 180 liters of another kind, and 240 liters of a third kind. He wants to sell the oil by filling the three kinds of oil in tins of equal capacity. What should be the greatest capacity of such a tin?

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English: These model solutions are structured to global academic standards for self-assessment and practice purposes. Students are advised to verify with official textbooks for board examinations.

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