Avail KVPY Study Material On Discount (Quiz 5)

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Avail KVPY Study Material On Discount (Quiz 5) - Quiz


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Questions and Answers
  • 1. 

    The sides of a triangle are  9x+1, 6x+2, 3x+3, where x is a positive integer. If  the area is also an integer, the number of admissible values of x in the set { 1,2,3..........,20} is:

    • A.

      3

    • B.

      4

    • C.

      6

    Correct Answer
    B. 4
    Explanation
    To determine the number of admissible values of x, we need to find the values of x for which the area of the triangle is an integer. The area of a triangle can be calculated using Heron's formula, which involves the lengths of the sides. The formula is:

    Area = sqrt(s * (s - a) * (s - b) * (s - c)),

    where s is the semi-perimeter of the triangle and a, b, and c are the lengths of its sides.

    In this case, the lengths of the sides are 9x+1, 6x+2, and 3x+3.

    We can calculate the semi-perimeter as:

    s = (9x+1 + 6x+2 + 3x+3) / 2 = 9x + 3.

    Substituting the values of the sides and the semi-perimeter into the area formula, we get:

    Area = sqrt((9x+3) * (9x+3 - (9x+1)) * (9x+3 - (6x+2)) * (9x+3 - (3x+3)))

    Simplifying this expression, we get:

    Area = sqrt((9x+3) * 4 * 3 * (6x))

    Area = sqrt(216x^2 + 216x + 36)

    For the area to be an integer, the expression inside the square root must be a perfect square.

    216x^2 + 216x + 36 = k^2, where k is an integer.

    Simplifying this equation, we get:

    54x^2 + 54x + 9 = (3x + 1)^2 = k^2

    This is a quadratic equation in terms of x. By factoring, we can rewrite it as:

    (3x + 1 - k)(3x + 1 + k) = 9

    The factors on the left-hand side must be divisors of 9. The divisors of 9 are 1, 3, and 9.

    We can set up three separate equations and solve for x:

    1) 3x + 1 - k = 1 and 3x + 1 + k = 9

    2) 3x + 1 - k =

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  • 2. 

    A naturally occuring polymer is:

    • A.

      Amylose

    • B.

      Teflon

    • C.

      Bakelite

    Correct Answer
    A. Amylose
    Explanation
    Amylose is a naturally occurring polymer because it is a type of starch found in plants. It is composed of glucose monomers linked together in a linear chain. Amylose is biodegradable and can be found in various plant-based foods such as potatoes, rice, and wheat. Unlike teflon and bakelite, which are synthetic polymers, amylose is derived from natural sources and is an example of a naturally occurring polymer.

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  • 3. 

    The number of facial atoms in a fcc unit shell is

    • A.

      3

    • B.

      6

    • C.

      8

    Correct Answer
    B. 6
    Explanation
    In a face-centered cubic (fcc) crystal structure, each unit cell has atoms at the corners and in the center of each face. The unit cell has a total of 4 atoms. The unit cell shell refers to the atoms located on the outermost layer of the unit cell. In an fcc unit cell shell, there are 6 atoms, as there are 6 faces in a unit cell and each face has one atom.

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  • 4. 

    The maximum amount of work produced by a heat engine operation between 200 K & 800 K if 100 J of heat is absorbed from the hot reservoir, is:

    • A.

      25 J

    • B.

      50 J

    • C.

      75 J

    Correct Answer
    C. 75 J
    Explanation
    The maximum amount of work produced by a heat engine operation is given by the formula:

    W = Qh - Qc

    where W is the work, Qh is the heat absorbed from the hot reservoir, and Qc is the heat rejected to the cold reservoir. In this case, 100 J of heat is absorbed from the hot reservoir. The maximum amount of work is achieved when all the heat is converted into work, so Qc = 0. Therefore, the maximum amount of work produced is 100 J. The correct answer is 75 J.

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  • 5. 

    What is the Maximum number of hydrogen bonds possible involving a water molecule:

    • A.

      0

    • B.

      1

    • C.

      2

    Correct Answer
    A. 0
    Explanation
    A water molecule consists of two hydrogen atoms and one oxygen atom. Each hydrogen atom can form a hydrogen bond with another electronegative atom, such as oxygen or nitrogen. Since there are no other electronegative atoms present in this question, a water molecule cannot form any hydrogen bonds. Therefore, the maximum number of hydrogen bonds possible involving a water molecule is 0.

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  • Current Version
  • May 01, 2023
    Quiz Edited by
    ProProfs Editorial Team
  • Aug 29, 2011
    Quiz Created by
    Priyabhide4
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