NSTSE 2023 previous year paper practice · PYQ-pattern set

NSTSE 2023 PYQ-pattern questions

Showing 10 of the 20 PYQ-pattern questions in this set — freshly worded in that year's pattern, not the original questions. Answers and solutions open under each question.

1. Q1 · Linear Equations in Two Variables

   The pair of linear equations 2x + 5y = 8 and 4x + 10y = 16 has:

   • A. A unique solution
   • B. Infinitely many solutions
   • C. No solution
   • D. Exactly two solutions
   Answer and solution

   Answer: B

   The second equation is exactly 2 times the first equation, meaning they represent the same line. Hence the system has infinitely many solutions.

2. Q2 · Circles

   Two tangents PA and PB are drawn to a circle with center O from an external point P. If ∠APB = 50°, then ∠AOB equals:

   • A. 130°
   • B. 100°
   • C. 120°
   • D. 140°
   Answer and solution

   Answer: A

   In quadrilateral OAPB, sum of angles = 360°. Since ∠OAP = ∠OBP = 90° (radius ⊥ tangent), we have 90° + 90° + 50° + ∠AOB = 360°, so ∠AOB = 130°.

3. Q3 · Mensuration

   A rectangular field has length 25 m and breadth 16 m. What is the area of the field?

   • A. 400 m²
   • B. 350 m²
   • C. 450 m²
   • D. 425 m²
   Answer and solution

   Answer: A

   The area of a rectangle is length × breadth = 25 × 16 = 400 m².

4. Q4 · Gravitation

   The value of acceleration due to gravity on the surface of Earth is approximately:

   • A. 8.8 m/s²
   • B. 9.8 m/s²
   • C. 10.8 m/s²
   • D. 11.8 m/s²
   Answer and solution

   Answer: B

   The standard value of acceleration due to gravity on Earth's surface is approximately 9.8 m/s².

5. Q5 · Light — Reflection and Refraction

   A concave mirror forms a real image of height 4 cm when the object of height 2 cm is placed 15 cm in front of it. What is the focal length of the mirror?

   • A. 5 cm
   • B. 10 cm
   • C. 15 cm
   • D. 20 cm
   Answer and solution

   Answer: B

   Magnification m = −v/u = h'/h = 4/2 = 2 (taking magnitude). Since real image, v = −30 cm. Using 1/f = 1/v + 1/u: 1/f = 1/(−30) + 1/(−15) = −1/10, so f = −10 cm (magnitude 10 cm).

6. Q6 · Atoms and Molecules

   How many moles of calcium carbonate (CaCO₃) are present in 25 g of it? (Given: Ca=40, C=12, O=16)

   • A. 0.15 moles
   • B. 0.20 moles
   • C. 0.25 moles
   • D. 0.30 moles
   Answer and solution

   Answer: C

   Molar mass of CaCO₃ = 40+12+(16×3) = 100 g/mol. Number of moles = 25/100 = 0.25 moles.

7. Q7 · Acids, Bases and Salts

   A solution changes the color of red litmus to blue. What is the nature of this solution?

   • A. Acidic
   • B. Basic
   • C. Neutral
   • D. Cannot be determined
   Answer and solution

   Answer: B

   Red litmus turns blue in a basic (alkaline) solution, indicating the presence of a base.

8. Q8 · Tissues

   Which type of tissue is responsible for the movement of our body parts?

   • A. Epithelial tissue
   • B. Connective tissue
   • C. Muscular tissue
   • D. Nervous tissue
   Answer and solution

   Answer: C

   Muscular tissue is responsible for movement in the body as muscle cells have the ability to contract and relax.

9. Q9 · Control and Coordination

   Which hormone is responsible for regulating blood sugar levels by promoting the uptake of glucose into cells?

   • A. Glucagon
   • B. Adrenaline
   • C. Insulin
   • D. Thyroxine
   Answer and solution

   Answer: C

   Insulin, produced by the pancreas, lowers blood glucose levels by facilitating cellular uptake of glucose and promoting its storage as glycogen.

10. Q10 · Life Processes

    During aerobic respiration in mitochondria, the maximum number of ATP molecules are produced in which stage?

    • A. Glycolysis
    • B. Krebs cycle
    • C. Electron transport chain
    • D. Fermentation
    Answer and solution

    Answer: C

    The electron transport chain produces approximately 34 ATP molecules, which is the maximum among all stages of aerobic respiration.