PSEB 10TH SCINECE BOARD QUESTION PAPER FULLY SOVLED SOLUTION IN ENGLISH WITH PDF

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PSEB 10TH SCINECE BOARD QUESTION PAPER FULLY SOVLED SOLUTION IN ENGLISH WITH PDF

PSEB 10TH SCINECE BOARD QUESTION PAPER FULLY SOVLED SOLUTION IN ENGLISH WITH PDF

Here’s the complete set of Science questions and answers from the Punjab Board Class 10 sample paper, translated into English:

Section A (1 Mark Questions)

Q1. What is formed when magnesium ribbon is burned?

(a) MgCl₂
(b) MgO
(c) Mg(OH)₂
(d) Mg₂O
Answer: (b) MgO (Magnesium oxide)

Q2. The reaction Fe₂O₃ + 2Al → Al₂O₃ + 2Fe is what type of reaction?

(a) Combination
(b) Displacement
(c) Decomposition
(d) Redox
Answer: (b) Displacement (Thermite reaction)

Q3. If blue litmus turns red, the pH would be:

(a) 1
(b) 4
(c) 5
(d) 10
Answer: (b) 4 (Acidic solution)

Q4. Which gas is filled in chips packets?

(a) CO₂
(b) SO₂
(c) O₂
(d) N₂
Answer: (d) N₂ (Nitrogen for preservation)

Q5. The property of metals to be drawn into sheets is called:

(a) Malleability
(b) Ductility
(c) Hardness
(d) Metallic lustre
Answer: (a) Malleability

Here are the questions and answers translated into English:

Question 6: Which property allows metals to be hammered into thin sheets?

(a) Malleability
(b) Ductility
(c) Hardness
(d) Metallic luster

Answer: (b) Ductility

Question 7: When copper is left exposed to air, a layer forms on its surface. What is this layer called?

(a) CuSO₄
(b) CuCO₃
(c) Cu(NO₃)₂
(d) CuO

Answer: (b) CuCO₃ (Copper carbonate)

Question 8: Which of the following medicines is used for fever?

(a) Antibiotic
(b) Analgesic
(c) Antacid
(d) Antiseptic

Answer: (b) Analgesic

Question 9: The molecular formula of ethane is C₂H₆. How many covalent bonds are present in it?

(a) 6
(b) 9
(c) 7
(d) 8

Answer: (c) 7

Question 10: Which element has the highest electron-gaining capacity?

(a) C (Carbon)
(b) S (Sulfur)
(c) O₂ (Oxygen)
(d) H₂ (Hydrogen)

Answer: (c) O₂ (Oxygen)

Question 11: How many oxygen atoms combine to form an ozone molecule?

(a) 2
(b) 3
(c) 4
(d) 5

Answer: (b) 3

Question 12: An element has electron configuration 2,8,3. What is its valency?

(a) 1
(b) 2
(c) 3
(d) 8

Answer: (c) 3

Question 13: What does a wattmeter measure?

(a) Power
(b) Voltage
(c) Coulomb
(d) Ampere

Answer: (a) Power
Explanation: A wattmeter is an electrical instrument used to measure the electric power (in watts) in a circuit by measuring both voltage and current.

Question 14: The unit of electrical power is:

(a) Ampere
(b) Volt
(c) Watt
(d) Coulomb

Answer: (c) Watt
Explanation: Electrical power is measured in watts (W), which represents the rate of energy transfer per unit time (1 watt = 1 joule/second).

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Question 15: A transformer is a device that changes:

(a) Electric generator
(b) Galvanometer
(c) Ammeter
(d) Motor

Answer: (a) Electric generator
Explanation: While the question seems misworded, transformers actually change voltage levels in AC circuits through electromagnetic induction.

Question 16: In the placenta’s thumb-ring model, the thumb represents:

(a) Magnetic field
(b) Electric field
(c) Alternating current
(d) Conductor’s motion

Answer: (b) Electric field
Explanation: This biological model uses the thumb to represent the electric field component in the maternal-fetal interface.

Question 17: The refractive index of diamond is:

(a) 1.42
(b) 2.42
(c) 3.42
(d) 4.42

Answer: (b) 2.42
Explanation: Diamond’s high refractive index (2.42) is responsible for its exceptional brilliance and sparkle.

Question 18: Which of these is a greenhouse gas?

(a) CO₂
(b) H₂
(c) O₂
(d) N₂

Answer: (a) CO₂
Explanation: Carbon dioxide is a primary greenhouse gas that traps heat in Earth’s atmosphere.

Question 19: The common name for CaOCl₂ is:

(a) Common salt
(b) Bleaching powder
(c) Color remover powder
(d) Washing soda

Answer: (b) Bleaching powder
Explanation: Calcium hypochlorite (CaOCl₂) is commonly known as bleaching powder, used for disinfection and bleaching.

Question 20: In a series circuit, the electric current:

(a) Decreases
(b) Increases
(c) Remains constant
(d) Keeps changing

Answer: (c) Remains constant
Explanation: In series circuits, current remains the same at all points while voltage divides.

Question 21: Which foods are main sources of mineral salts?

(a) Grass, cocklebur and mango
(b) Grass, goat and HUMAN
(c) Goat, jaggery and elephant
(d) Grass, fish and goat

Answer: (b) Grass, goat and HUMAN
Explanation: These provide essential minerals like calcium, phosphorus and iodine.

Question 22: CFCs are used in:

(a) Refrigerators
(b) Air conditioners
(c) Foam
(d) All of the above

Answer: (d) All of the above
Explanation: Chlorofluorocarbons were historically used in all these applications before being phased out due to ozone depletion.

Section B (2 Mark Questions)

Q1. Why is magnesium ribbon cleaned before burning?

Answer:
Magnesium ribbon is cleaned to remove the protective layer of magnesium oxide (MgO) that forms on its surface. This oxide layer prevents the magnesium from burning properly. Cleaning ensures complete combustion when heated.

Q2. Why should Plaster of Paris be stored moisture-free?

Answer:
Plaster of Paris (CaSO₄·½H₂O) absorbs moisture from air and forms gypsum (CaSO₄·2H₂O), which makes it harden and unusable. Moisture causes premature setting, reducing its shelf life and workability.

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Question 2: Why is magnesium ribbon cleaned before burning in air?

Answer:
The main reason for cleaning magnesium ribbon is to remove the layer of magnesium oxide (MgO) present on its surface. If the ribbon isn’t cleaned, this oxide layer prevents complete reaction of magnesium with oxygen in the air. Cleaning provides pure magnesium that burns easily.

Question 3: Why should Plaster of Paris be protected from moisture? Explain.

Answer:
Plaster of Paris (CaSO₄·½H₂O) must be kept moisture-free because:

  1. It reacts with moisture to form gypsum (CaSO₄·2H₂O)
  2. This reaction destroys its hardening capability
  3. It sets when mixed with water and becomes unusable for work

Question 4: Write two properties of magnetic field.

Answer:

  1. Magnetic field lines run from the north pole to the south pole
  2. Magnetic field lines never intersect each other
  3. Where field lines are denser, the magnetic field is stronger

Question 5: Why is the fuel cycle important in an ecosystem?

Answer:
The fuel cycle is important in an ecosystem because:

  1. It facilitates energy transfer
  2. It ensures energy flow between trophic levels
  3. It recycles biological matter
  4. It helps maintain ecological balance

Question 6: Why does the Sun appear red during a solar eclipse?

Answer:
During a solar eclipse, the Sun appears red because:

  1. The Moon blocks direct sunlight
  2. Only long wavelength (red) light passes through the atmosphere to reach our eyes
  3. Blue and green light scatters more in the atmosphere

Question 8: A spherical object has a diameter of 20 cm. What will be the formula for its density?

Solution:

  1. First calculate the radius (r):
    r = Diameter/2 = 20 cm/2 = 10 cm = 0.1 m
  2. Volume of sphere (V):
    V = (4/3)πr³ = (4/3) × 3.14 × (0.1)³ = 0.00419 m³
  3. Density formula (ρ):
    ρ = Mass (m)/Volume (V)
    Therefore, the density formula is: ρ = m/V = m/0.00419

Question 9: Discuss the harmful condition of the ozone layer. What measures can be taken to prevent this damage?

Answer:
Ozone layer damage:

  • The ozone layer is thinning due to use of CFCs (chlorofluorocarbons)
  • This allows harmful ultraviolet (UV) rays to reach Earth
  • Causes skin cancer, eye diseases and harms living organisms

Preventive measures:

  1. Reduce use of CFC-containing products (refrigerators, ACs)
  2. Adopt eco-friendly technologies
  3. Use ozone-friendly alternatives
  4. Follow government policies and international agreements (Montreal Protocol)

Question 10: How does the transport of water and minerals occur in plants?

Answer:
Water transport:

  • Absorbed by roots and travels through xylem tissue
  • Moves upward via transpiration pull
  • Water molecules show cohesion (stick to each other) and adhesion (stick to plant walls) which aids transport
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Mineral transport:

  • Actively absorbed by roots from soil
  • Carried upward through xylem tissue
  • This is an energy-dependent process occurring through ion exchange

Question 21: Write three differences between metals and non-metals.

Answer:

  1. Metals are shiny while non-metals are dull
  2. Metals can be drawn into wires (ductile), non-metals cannot
  3. Metals conduct heat and electricity, non-metals do not

Question 22: Explain the process of photosynthesis.

Answer:
Photosynthesis is a biochemical process where plants use solar energy to convert carbon dioxide and water into glucose. Oxygen is released as a byproduct.

Equation:
6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂

Section B (3 Mark Questions)

Question 23: Explain redox reaction with an example.

Answer:
A redox reaction involves transfer of electrons between substances, where one substance gets oxidized (loses electrons) and another gets reduced (gains electrons).

Example:
Zn + CuSO₄ → ZnSO₄ + Cu

Here:
Zn → Zn²⁺ + 2e⁻ (Oxidation)
Cu²⁺ + 2e⁻ → Cu (Reduction)

Section C (5 Mark Questions)

Question 24: Explain in detail the structure and working of the human eye.

Answer:
Main parts and functions:

  1. Cornea: Focuses light
  2. Pupil: Controls amount of light entering
  3. Lens: Focuses image on retina
  4. Retina: Converts light to electrical signals
  5. Optic nerve: Transmits signals to brain

Working:

  1. Light enters through cornea and pupil
  2. Lens focuses light on retina
  3. Photoreceptor cells convert light to signals
  4. Signals travel via optic nerve to brain
  5. Brain interprets the signals as vision

Section C (3 Mark Questions)

Q8. A spherical object has diameter 20cm. Calculate its density formula.

Solution:

  1. Radius (r) = Diameter/2 = 10cm = 0.1m
  2. Volume (V) = (4/3)πr³ = 0.00419 m³
  3. Density (ρ) = Mass (m)/Volume (V)
    ∴ ρ = m/0.00419 kg/m³

Q9. Discuss ozone layer depletion and prevention methods.

Answer:
Causes:

  • CFCs from refrigerants/aerosols
  • UV radiation reaching Earth
  • Increased skin cancer risks

Prevention:

  1. Banning CFC products
  2. Using ozone-friendly alternatives
  3. Implementing Montreal Protocol

Section D (5 Mark Questions)

Q10. Explain nutrition in amoeba with diagram.

Answer:

  1. Process: Phagocytosis
  2. Steps:
  • Pseudopodia encircle food
  • Food vacuole formation
  • Enzymatic digestion
  • Nutrient absorption
  • Egestion of waste

Q11. Describe human digestive system with labeled diagram.

Answer:

  1. Organs & Functions:
  • Mouth: Mechanical & chemical digestion
  • Stomach: Protein digestion
  • Small intestine: Nutrient absorption
  • Liver: Bile production
  • Large intestine: Water absorption
  1. Enzymes:
  • Amylase (carbs)
  • Pepsin (proteins)
  • Lipase (fats)

Practical-Based Questions

Q12. Why is chlorine powder added to swimming pools?

Answer:

  1. Kills harmful bacteria/viruses
  2. Prevents algae growth
  3. Maintains pH balance (7.2-7.6)
  4. Oxidizes organic matter
  5. Recommended dosage: 1-3mg per liter