Madhyamik Class 10 Physical Science Question Paper Solved 2022

a. Troposphere

Explanation:

The troposphere is the lowest layer of Earth’s atmosphere and contains approximately 75% of the atmosphere’s mass, making it the densest layer.

(b)

Explanation:

The P-V graph (Pressure vs. Volume) related to Boyle’s Law is a curve that shows an inverse relationship between pressure (P) and volume (V) of a gas at constant temperature.

(d) M = 2D

Explanation: Molecular mass is twice the vapour density of a substance.

(c) 10 cm

Explanation: The focal length (f) of a concave mirror is half of its radius of curvature (R).

So, f = 20over2 = 10 cm

(b) Infrared ray

Explanation: Infrared rays have a longer wavelength than visible light, while X-rays, gamma (γ) rays and ultraviolet rays have shorter wavelengths than visible light.

(c) Concave mirror

Explanation: Dentists use concave mirrors because they produce a magnified and upright image of the teeth, which helps in detailed examination.

(b) -1.6 × 10⁻¹⁹ C

Explanation: The charge of an electron is negative and its magnitude is 1.6 × 10⁻¹⁹ coulombs.

(c) H ∝ I²

Explanation: According to Joule’s law of heating, the heat produced in a conductor is given by:

H = I2Rt

(b) 0.1 amperes

Explanation:

Q = 12 C (charge)

t = 2 min = 2 × 60 = 120 seconds

Current (I) is calculated using the formula:

I = 12/120 = 0.1 A

So, the electric current is 0.1 amperes.

(c) 18

Explanation: The long periodic table has 18 groups (columns) that categorize elements based on their similar chemical properties.

(d) F > Cl > Br > I

Explanation: In Group 17 (halogens), the oxidizing power decreases down the group. Fluorine (F) is the strongest oxidizing agent, followed by chlorine (Cl), bromine (Br), and iodine (I).

(a) LiH

Explanation: In lithium hydride (LiH), lithium (Li) has only 2 electrons in its outer shell after bonding (duplet), and hydrogen (H) also has 2 electrons (which is a complete shell for it). Thus, neither ion achieves an octet configuration. In the other compounds, the ions achieve an octet configuration.

(c) Partially dissociated

Explanation: Acetic acid (CH₃COOH) is a weak electrolyte because it does not completely dissociate in aqueous solution; instead, it partially ionizes into acetate ions (CH₃COO⁻) and hydrogen ions (H⁺).

d. Reduction occurs at the cathode and oxidation occurs at the anode.

Explanation: During electrolysis, reduction (gain of electrons) takes place at the cathode, while oxidation (loss of electrons) occurs at the anode.

One alternative fuel to fossil fuels is biofuel.

A gas that increases atmospheric temperature is carbon dioxide (CO₂)

OR

Ultraviolet (UV) radiation, coming from the sun, is prevented by the ozone layer from falling on the earth’s surface.

The SI unit of pressure of a gas is the pascal (Pa).

In Charles’ law, the constants are pressure and the mass of gas.

OR

True: Per degree interval in the Kelvin scale is equal to per degree interval in the Celsius scale.

Yes, it is possible to form a virtual image of a shorter length than the length of the object using a concave mirror.

A concave mirror is used in the headlight of a motor car.

μ_r < μ_b

The SI unit of electric charge is the coulomb (C).

The unit of electrical conductance is the Siemens (S).

OR

Fuse wire is made of an alloy of tin (Sn) and lead (Pb). The alloy is usually made up of 62% tin and 38% lead.

‘Kilowatt-hour’ is the unit of energy.

2.11.1 Acetic acid → (b) Weak electrolyte

2.11.2 Glass → (a) non-conductor of electricity

2.11.3 Most electro-negative element → (d) Fluorine

2.11.4 One noble element → (c) Krypton

F > Cl > Br > I

Group 17 (Halogens) of the long periodic table contains elements in all three physical states: gaseous (e.g., F, Cl), liquid (e.g., Br), and solid (e.g., I).

OR

The alkali metals belong to Group 1 of the long periodic table.

The conventional representation of an H₂O molecule using ‘dash’ signs is

H – O – H

The hydride ion (H⁻) has gained an extra electron, giving it an electronic configuration similar to that of helium (He), which is 2.

OR

The Lewis dot diagram for the H₂ molecule is represented as follows:

H : H

An example of a covalent liquid is water (H₂O).

False.

The electrical conductivity of fused NaCl is greater than that of solid NaCl because, in the solid state, NaCl does not have free ions to conduct electricity.

At the cathode in the electrolyte method of aluminium extraction, aluminium ions (Al³⁺) are reduced to form aluminium metal (Al). The reaction is:

Al³⁺ +3e⁻ →Al

OR

False. Free ions, not free electrons, carry electricity through electrolytic substances.

Global warming is the gradual increase in Earth’s average surface temperature due to the buildup of greenhouse gases, such as carbon dioxide (CO₂) and methane (CH₄), in the atmosphere. These gases trap heat from the sun, causing a rise in temperature, which leads to climate changes like melting ice caps, rising sea levels, and more extreme weather patterns.

Initial pressure (P₁) ​ = 770 mm Hg

Initial volume (V₁) ​ = 75 cm³

Final pressure (P₂) ​ = 750 mm Hg

Final volume (V₂) ​ =?

Apply Boyle’s Law:

P₁​V₁​ = P_2​V₂

​Or, V₂ = P_1​V_1​over P_2

or, V₂ = 770 × 75over 750 = 77 cm³

The volume of hydrogen gas at 750 mm Hg pressure will be 77 cm³.

OR

Mass of O₂ = 64 g

Pressure (P) = 2 atm

Temperature (T) = 300 K

R = 0.082 L·atm·mol⁻¹·K⁻¹

Molar mass of O₂ (O = 16) = 32 g

mole (n) = mass of O_2over molar mass of O_2 = 2

The ideal gas law is: PV = nRT

V = nRTover P

V = 2 × 0.082 × 300over 2

V = 2 × 0.082 × 300over 2 = 24.6

The volume of 64 g of O₂ gas at 2 atm and 300 K is 24.6 litres.

The angle of deviation (δ) for light rays passing from a rarer to a denser medium is given by:

δ = i−r

Where:

• i is the angle of incidence,
• r is the angle of refraction.

OR

Green leaves appear green because they contain a pigment called chlorophyll, which absorbs most of the blue and red wavelengths of light and reflects the green wavelength. Since green light is reflected, it is the colour we see.

The electromotive force (emf) of an electric cell in an open circuit is the maximum potential difference between the two terminals of the cell when no current is flowing through the circuit. It represents the total energy provided by the cell per unit charge to move it through the circuit.

The elements of Group 2 in the long periodic table are called alkaline earth metals because:

1. Their oxides and hydroxides are alkaline (basic) in nature, meaning they can neutralize acids.
2. These metals are found in the earth’s crust as compounds, hence the term “earth” metals.

OR

An example of a transitional element is iron (Fe), and an example of a transuranic element is plutonium (Pu).

Ammonia (NH₃) has covalent bonds.

Lewis electron dot diagram of NH₃ :

In sodium fluoride (NaF), an ionic bond forms through the transfer of electrons:

• Sodium (Na) loses one electron (2, 8, 1 → 2, 8) to become Na⁺.
• Fluorine (F) gains one electron (2, 7 → 2, 8) to become F^–.

The electrostatic attraction between Na⁺ and F⁻ creates the ionic bond in NaF.

OR

Lewis dot diagram of CO₂ molecule:

Strong Electrolyte

A substance that completely dissociates into ions in water and conducts electricity very well is called a strong electrolyte.

Examples – sodium chloride (NaCl) and potassium nitrate (KNO₃).

Cathode and Anode

The electrode where reduction takes place and which attracts cations during electrolysis is called the cathode.

The electrode where oxidation takes place and which attracts anions during electrolysis is called the anode.

Let V be the volume of a given mass of gas at pressure P and temperature T (absolute),

From Boyle’s law: V ∝ 1/P (m and T constant)

From Charle’s law: V ∝ T (m and P constant)

By combining two laws we have,

V ∝ T/P or,

V = K T/P (Where K = proportionality constant)

or, PV = KT

or, PV = nRT

Where n is the number of moles of gas, R is the universal gas constant (0.08206 L·atm/mol·K)

Given

• Mass of metallic oxide = 40 grams
• Mass of metal produced = 28 grams
• Mass of aluminum oxide produced = 25.5 grams

Let’s assume the mass of aluminum required for the reaction is $x$ grams.

According to the law of conservation of mass:

Mass of reactants = Mass of products

⇒ 40 + x = 28 + 25.5

⇒ x = 53.5- 40 = 13.5 g

∴ 13.5 grams of aluminum are required for the reaction.

OR

Molar mass of H₂SO₄ = 2 + 32 + 4×16 = 98 g

Molar mass of NaOH = 23 + 16 + 1 = 40 g

From the balanced chemical equation:

H₂SO₄ + 2NaOH → Na₂SO₄ + 2H₂O

98 g             80 g

Amount of NaOH required to completely react with 98 g H₂SO₄  = 80 g

∴ Amount of NaOH required to completely react with 4.9 g H₂SO₄ = 80over 98 × 4.9 = 4.0 g

Finding the wavelength:

μ = 1.5

λ_medium ​= 4000 Å

λ_air = μ × λ_medium ​

⇒ λ_air = 1.5 × 4000 = 6000 Å

Find the velocity: 

μ = 1.5

v_air ​= 3 × 10⁸ m/s

v_medium = 3 × 10⁸/1.5 = 2 × 10⁸ m/s

OR

Angle of deviation (δ) = 40º

Angle of prism (A) = 60º

We know, δ = 2i−A

⇒ i = δ + Aover 2

⇒ i = 40º + 60ºover 2 = 50º

The angle of incidence at the first surface of the prism is 50°.

Ray Diagram for convex lens:

OR

Converging action of the convex lens as a combination of prisms:

A lens is made up of a set of prisms, the prisms in the upper part of a convex lens have their bases downwards, while the prisms in the lower part of the lens have their bases upwards. When a beam of parallel rays of light incident on a convex lens, the prisms in the upper part of the lens bend the incident rays downward and the prisms in the lower part of the lens bend the incident rays upwards. The central part which is a parallel sided glass block passes the incident ray undeviated. Thus the convex lens converges the parallel beam of light to a point called principal focus (F) of the lens and hence a convex lens is called a converging lens.

Long-sightedness, also known as hypermetropia, is a vision defect in which a person can see distant objects clearly but has difficulty focusing on nearby objects. This happens because the image of close objects is formed behind the retina instead of directly on it, often due to a shorter-than-normal eyeball or a less curved cornea.

To correct long-sightedness, a convex lens is used.

Find resistance of each (R = V²/P):

R₆₀ = 240² / 60

= 57600 / 60

= 960 Ω

R₁₀₀ = 240² / 100

= 57600 / 100

= 576 Ω

Series current:

R_total = 960 + 576 = 1536 Ω

I = V / R_total = 240 / 1536 = 0.15625 A

Power in each (P = I²R):

P₆₀ = (0.15625)² × 960 = 23.44 W

P₁₀₀ = (0.15625)² × 576 = 14.06 W

Conclusion: The 60 W bulb (higher resistance) dissipates more power in series and shines brighter.

Thus, the 60W bulb will shine brighter than the 100W bulb in this series connection.

OR

EMF = electromotive force of the cell = 2 V

r = internal resistance of the cell = 5 Ω

R = external resistor = 15 Ω

R_Total = R + r = 15 + 5 = 20 Ω

Current (I) = 2over 20 = 0.1 A

V = EMF − I⋅r = 2V – (0.1 A × 5 Ω) = 1.5 V

Thus, the potential difference between the two ends of the cell is 1.5 V.

In an electric motor, electrical energy is transformed into mechanical energy.

Domestic Circuits Use Parallel Combination because

1. Each appliance gets the same voltage, ensuring it works properly.
2. If one appliance fails, others still work. This prevents disruptions.
3. Each appliance has its own switch allowing for easy operation of each appliance.

Ohm’s Law states that the current (I) flowing through a conductor is directly proportional to the voltage (V) across it, provided the temperature remains constant.

Mathematically, it is expressed as: V = I × R

Given Data

• Potential Difference (V) = 10 V
• Current (I) = 0.1 A

R = Vover I = 10over 0.1 = 100 Ω

Atomic Radius: Se > S > O

Electronegativity: O < S < Se

Ionization Energy: Se < S < O

MgCl₂ (magnesium chloride) contains ionic bonds.

Formation of Chemical Bonds in MgCl₂

• Magnesium tends to lose its two valence electrons to achieve a stable electron configuration, forming a Mg²⁺ ion.
• Each chlorine atom can gain one electron to complete its octet, forming two Cl^– ions.
• The Mg²⁺ ion and the two Cl^– ions attract each other due to opposite charges, resulting in the formation of MgCl₂ through ionic bonding.

OR

An aqueous solution of sodium chloride (NaCl) conducts electricity because NaCl is an ionic compound. When dissolved in water, it dissociates into free-moving Na⁺ and Cl⁻ ions, which carry electric charge and enable the flow of current.

Whereas, sugar or glucose are covalent compounds that do not dissociate into ions when dissolved in water. Since there are no free-moving charged particles in the solution, it cannot conduct electricity.

Electroplating is a process that uses electric current to deposit a layer of metal onto a surface. This technique is often used to enhance the appearance, corrosion resistance, and conductivity of the material being plated.

In the electroplating of silver over copper, the copper object being coated serves as the cathode.

In the electrolysis of acidulated water, the reaction occurring at the cathode (where reduction takes place) is:

2H⁺ + 2e⁻→ H₂​↑

Acidulated Water is Used

1. Increased Conductivity: Acidulated water has more ions, improving conductivity compared to pure water.
2. Faster Reaction: The presence of H⁺ ions accelerates hydrogen gas formation at the cathode, making electrolysis more efficient.

OR

Reactions in Electrolysis of CuSO₄ with Cu Electrodes

• At the Cathode: Cu²⁺ + 2e ⁻ → Cu (s)
• At the Anode: Cu (s) → Cu²⁺ + 2e⁻

In the refining of impure copper, the anode used is made of impure copper metal.

The SI unit of calorific value of fuels is joules per kilogram (J/kg).

PV=RT (where, n = 1)

The transitional elements are located from Group 3 to Group 12 of the long periodic table.

In a dynamo, mechanical energy is transformed into electrical energy.

In a CHCl₃ (chloroform) molecule, there are four covalent bonds.

For parallel Combination: {1over R_{eq}} = {1over R_1}  + {1over R_2}

or, {1over R_{eq}} = {1over 6}  + {1over 4}

or, {1over R_{eq}} = {2 + 3over 12}

or, Req = 2.4 Ω

The principal axis of a concave lens is an imaginary straight line that runs horizontally through the center of the lens. It helps measure angles of light as they pass through the lens.

Hydrogen shares similarities with group 17 elements (halogens) in the following ways:

1. Both hydrogen and halogens have valency one.
2. Both hydrogen and halogens exist as diatomic molecules (H₂, F₂, Cl_2, Br₂) in their gaseous states.

Fused sodium chloride can conduct electricity because, when it is melted (fused), the ionic bonds holding the Na⁺ and Cl⁻ ions in a rigid structure are broken. This allows the ions to move freely in the molten state. The movement of these charged ions enables the conduction of electric current.

For parallel Combination: frac{1}{R_{eq}} = frac{1}{R_1} + frac{1}{R_2}

or, frac{1}{R_{eq}} = frac{1}{6} + frac{1}{4}

or, frac{1}{R_{eq}} = frac{2 + 3}{12}

or, R_{eq} = 2.4 , Omega