TS Class 10 Physical Science Solved Public Exam Paper 2021 - Physics & Chemistry Solutions, & Part-B

📄 Official Board Exam Solution — 2021

TS SSC Physical Science 2021 Public Exam Solved Paper

Complete Step-by-Step Official Solutions: Physics & Chemistry Sections, Ray Diagrams, Circuit Numericals, Chemical Reactions & Part-B Objective MCQs

📌 2021 Board Examination Pattern & Weightage Summary

1. Total Weightage & Time

Total Marks: 40 Marks (Part-A: 35 Marks + Part-B: 5 Marks) | Duration: 1 Hour 30 Minutes

Part-A = 35 Marks  |  Part-B = 5 Marks (10 MCQs)

2. Physics Section Weightage

Optics, Refraction at Curved Surfaces, Electric Current, and Electromagnetism:

Physics Section = 20 Marks

3. Chemistry Section Weightage

Chemical Reactions, Acids & Bases, Atomic Structure, Periodic Table & Metallurgy:

Chemistry Section = 20 Marks

📊 TS SSC 2021 Question Paper Key Topics Analysis

High-priority topics that appeared in the official 2021 Telangana Class 10 Public Examination:

High Weightage Chapters in 2021 Paper

1. Refraction at Curved Surfaces

Featured Question: Convex lens ray diagram for object placed between F₁ and 2F₁ & Lens Formula calculation.

2. Electric Current & Circuits

Featured Question: Solved parallel resistor combination numerical & experimental verification of Ohm's Law.

3. Structure of Atom & Bonding

Featured Question: 4 Quantum Numbers set for 3d orbital electron & VSEPR shape of H₂O and NH₃.

4. Chemical Reactions & Metallurgy

Featured Question: Balancing chemical equations, Calcination vs Roasting, and Thermite Welding process.

Exam Tip for TS Board Students: Step-wise working, proper SI units in physics numericals, and balanced chemical equations are essential to secure 100% marks in evaluation.

⚡ Physics Section Solved Questions (Part-A)

PHYSICS - 2 MARKS

Q1. State Snell's Law of Refraction. Write its mathematical expression and name the terms.

Answer:

• Snell's Law: The ratio of the sine of the angle of incidence (i) to the sine of the angle of refraction (r) is constant for a given pair of media and a given wavelength of light.
• Mathematical Expression:
  n₁ × sin(i) = n₂ × sin(r)   or   sin(i) / sin(r) = n₂₁ = n₂ / n₁
• Where:
  • i = Angle of incidence in medium 1
  • r = Angle of refraction in medium 2
  • n₁ = Refractive index of first medium
  • n₂ = Refractive index of second medium

PHYSICS - 4 MARKS SOLVED NUMERICAL

Q2. Two resistors of 4 Ω and 12 Ω are connected in parallel across a 6 V battery. Calculate:
(a) Equivalent resistance of the circuit.
(b) Total current drawn from the battery.

Given Data: R₁ = 4 Ω, R₂ = 12 Ω, Battery Voltage V = 6 V

(a) Calculating Equivalent Resistance (R_eq) in Parallel:

1 / R_eq = 1 / R₁ + 1 / R₂

1 / R_eq = 1 / 4 + 1 / 12 = (3 + 1) / 12 = 4 / 12 = 1 / 3

R_eq = 3 Ω

(b) Calculating Total Current (I) using Ohm's Law (I = V / R_eq):

I = 6 V / 3 Ω = 2 A

✓ Final Answer:
1. Equivalent Resistance R_eq = 3 Ω.
2. Total Circuit Current I = 2 A.

PHYSICS - 6 MARKS ESSAY & RAY DIAGRAM

Q3. An object is placed between F₁ and 2F₁ in front of a Convex Lens. Describe the position, nature, and characteristics of the image formed. Draw a schematic ray diagram.

Answer:

• Position of Object: Between F₁ and 2F₁ in front of the convex lens.
• Position of Image: Formed beyond 2F₂ on the opposite side of the lens.
• Nature and Characteristics of Image:
  1. Nature: Real and Inverted.
  2. Size: Magnified (Larger than the object).
  3. Magnification (m): Negative and greater than 1 (|m| > 1).

Ray Tracing Rules Used:

1. Ray parallel to principal axis passes through focus F₂ after refraction.

2. Ray passing through the Optic Center (O) goes undeviated.

3. Both refracted rays meet beyond 2F₂ to form a magnified real inverted image.

🧪 Chemistry Section Solved Questions (Part-A)

CHEMISTRY - 2 MARKS

Q4. Write the set of four Quantum Numbers for the outer electron of a Sodium atom (Na, Z = 11).

Answer:

• Sodium (Na, Z = 11): Electronic configuration = 1s² 2s² 2p⁶ 3s¹.
• The outer electron enters the 3s orbital (3s¹).
• 4 Quantum Numbers for 3s¹ electron:
  • Principal Quantum Number (n) = 3
  • Angular Momentum Quantum Number (l) = 0 (for s-subshell)
  • Magnetic Quantum Number (m_l) = 0
  • Spin Quantum Number (m_s) = +½ (or -½)

CHEMISTRY - 4 MARKS

Q5. Differentiate between Calcination and Roasting with suitable balanced chemical equations.

Feature	Calcination	Roasting
Heating Environment	Heating ore strongly in absence or limited air.	Heating ore strongly in excess air.
Ore Type	Carbonate and Hydrated ores.	Sulphide ores.
Reaction Equation	ZnCO3(s) →Δ→ ZnO(s) + CO2(g)↑	2ZnS(s) + 3O2(g) →Δ→ 2ZnO(s) + 2SO2(g)↑

CHEMISTRY - 6 MARKS ESSAY

Q6. Explain the trend of Atomic Radius, Ionization Energy, and Electronegativity across a Period (Left to Right) and down a Group (Top to Bottom) in the Modern Periodic Table.

Answer:

Periodic Property	Across a Period (Left to Right)	Down a Group (Top to Bottom)
1. Atomic Radius	Decreases (Nuclear charge increases, pulling electrons closer).	Increases (New electron shells are added).
2. Ionization Energy (IE)	Increases (Smaller atomic size increases attraction on valence electrons).	Decreases (Valence electrons farther from nucleus and shielded).
3. Electronegativity (EN)	Increases (Fluorine in Group 17 has highest EN = 4.0).	Decreases (Atomic radius increases down the group).

🎯 PART-B Objective Bits Bank (10 MCQs - Official 2021 Paper)

BIT 1

1. The focal length of a convex lens is +20 cm. Its power in dioptres is:

• +2.0 D
• +5.0 D
• -5.0 D
• +0.2 D

✓ Correct Option: B (P = 100 / f = 100 / 20 = +5.0 D)

BIT 2

2. Which light ray undergoes NO deviation when passing through a lens?

• Ray parallel to principal axis
• Ray passing through Optic Center (O)
• Ray passing through Focus (F)
• Ray making 45° angle with lens

✓ Correct Option: B (Ray passing through Optic Center)

BIT 3

3. What is the SI unit of Specific Resistance (Resistivity)?

• Ohm (Ω)
• Ohm-meter (Ω·m)
• Volt/Ampere
• Watt

✓ Correct Option: B (Ohm-meter Ω·m)

BIT 4

4. Fleming's Left Hand Rule is used to determine the direction of force in an:

• AC Generator
• Electric Motor
• Transformer
• Galvanometer

✓ Correct Option: B (Electric Motor)

BIT 5

5. Which element has the highest electronegativity in the Modern Periodic Table?

• Chlorine (Cl)
• Fluorine (F)
• Oxygen (O)
• Cesium (Cs)

✓ Correct Option: B (Fluorine - F)

BIT 6

6. What is the shape of a p-orbital?

• Spherical
• Dumbbell
• Double dumbbell
• Linear

✓ Correct Option: B (Dumbbell)

BIT 7

7. Bauxite is the principal ore of which metal?

• Iron (Fe)
• Aluminium (Al)
• Copper (Cu)
• Zinc (Zn)

✓ Correct Option: B (Aluminium Al₂O₃·2H₂O)

BIT 8

8. The functional group present in Ethanoic Acid (−COOH) is:

• Alcohol
• Aldehyde
• Ketone
• Carboxylic Acid

✓ Correct Option: D (Carboxylic Acid)

BIT 9

9. Kirchhoff's Junction Law (∑I = 0) is based on the Law of Conservation of:

• Energy
• Charge
• Mass
• Momentum

✓ Correct Option: B (Conservation of Charge)

BIT 10

10. The IUPAC name of the compound CH₃−CH₂−OH is:

• Methanal
• Ethanol
• Ethanal
• Ethanoic Acid

✓ Correct Option: B (Ethanol)