Madhyamik Class 10 Physical Science Question Paper Solved 2017

d. Oxygen

Explanation: Greenhouse gases, such as methane, water vapour, and carbon dioxide, trap heat in the Earth’s atmosphere and contribute to the greenhouse effect. Oxygen, however, does not have this property. It is a major component of the atmosphere but does not significantly contribute to the greenhouse effect.

b. Nm^-2

c. 32

Explanation: The molecular weight of the gas is 2 × 32 = 64

c. nature of the material.

Explanation: Thermal conductivity is a property intrinsic to the material itself, reflecting how well it can conduct heat.

c. Violet

Explanation: When white light passes through a prism, it is dispersed into its component colours (spectrum). The degree of deviation depends on the wavelength of the light. Violet light has the shortest wavelength and is refracted (bent) the most, while red light, having the longest wavelength, deviates the least.

b. volt-ohm^-1

Explanation: According to Ohm’s Law, I = V/R , where I is the current in amperes, V is the voltage in volts, and R is the resistance in ohms. Thus, an ampere can be represented as a volt divided by ohm, or V ohm^{− 1} Vohm⁻¹.

b. semiconductor

Explanation: In semiconductors, as temperature increases, more electrons gain enough energy to move from the valence band to the conduction band, resulting in an increase in charge carriers (electrons and holes). This leads to a decrease in resistivity.

a. α > β > γ.

Explanation: Alpha (α) particles have the highest ionizing power because they are large, heavy, and carry a +2 charge. Beta (β) particles, which are high-energy electrons, have moderate ionizing power, while gamma (γ) rays are high-energy electromagnetic waves and have the least ionizing power because they do not have mass or charge.

a. K

Explanation: Atomic radius increases as you move down a group in the periodic table because additional electron shells are added, making the atom larger. In this case, potassium (K) is below sodium (Na), lithium (Li), and hydrogen (H) in Group 1, so it has the largest atomic radius among them.

a. hydrogen chloride

Explanation: In hydrogen chloride, the bond between hydrogen and chlorine is a covalent bond, where electrons are shared between the two atoms. Sodium chloride (NaCl), lithium hydride (LiH), and calcium oxide (CaO) all involve ionic bonds, where electrons are transferred from one atom to another, leading to the formation of positive and negative ions.

a. CH₃COOH

Explanation: A weak electrolyte is a substance that only partially ionizes in solution. Acetic acid (CH₃COOH) is a weak acid and only partially dissociates into ions in water. In contrast, NaOH (sodium hydroxide), H₂SO₄ (sulfuric acid), and NaCl (sodium chloride) are strong electrolytes, meaning they fully dissociate into ions in aqueous solution.

b. P₂O₅

Explanation: Phosphorus pentoxide is a powerful desiccant that effectively absorbs water from gases, including ammonia.

a. Bauxite

Explanation: Bauxite is the primary ore from which aluminium is extracted. Hematite is an ore of iron, malachite is an ore of copper, and chalcopyrite is also an ore of copper.

b. -CHO

Explanation: The aldehyde functional group consists of a carbonyl group (C=O) bonded to a hydrogen atom, giving the structure -CHO. The group >C=O represents the carbonyl group, which is also found in ketones.

In the troposphere, temperature decreases with an increase in altitude.

Or

One harmful effect of global warming

• Rising Sea Levels: Melting polar ice and thermal expansion of seawater lead to coastal flooding and erosion.
• Extreme Weather Events: Increased frequency and intensity of hurricanes, heatwaves, and heavy rainfall.  (Anyone point)

False.

Explanation: Under the same conditions of temperature and pressure, equal volumes of any gases, including CO₂ and N₂, contain the same number of molecules according to Avogadro’s law.

At constant temperature, the volume of the given mass of the gas is inversely proportional to the pressure of the gas.PV = constant

Between the apparent and real expansion coefficients of a liquid, the real expansion coefficient is its own characteristic.

OR

The SI unit of thermal conductivity is watt per meter-kelvin (W/m·K).

Work = 1 C × 1 V = 1 joule

So, 1 joule of work has to be done.

A β-particle (beta particle) is emitted from the nucleus of a radioactive atom.

OR

• The new atomic number = 92 – 2 = 90
• The new mass number = 238 – 4 = 234

Thus, the daughter element produced is ₉₀T²³⁴ (Thorium)

1. A transition element. – (b) Nickel2. A transuranium element. – (d) Plutonium

3. Reduces Fe_₂SO_₃ at high temperatures in the thermit process. – (a) Aluminium

4. Present in the alloy bell metal. – (c) Tin

The electrical conductivity increases because sulfuric acid dissociates into ions (H⁺ and SO₄²⁺), which carry an electric current, unlike pure water.

OR

The carriers of electricity during electrolysis are ions—cations (positive) and anions (negative).

OR

An isomer of CH₃CH₂OH (ethanol) is dimethyl ether (CH₃OCH₃).

Here is its constitutional formula:

H₃C—O—CH₃.

This is an example of a functional group isomer, where ethanol is an alcohol and dimethyl ether is an ether.

The calorific value of a fuel is the amount of heat energy produced when a given amount of the fuel is completely burned. It is usually expressed in joules per kilogram (J/kg) or kilocalories per kilogram (kcal/kg).

Between coal and diesel, diesel has a greater calorific value.

Initial volume (V₁) = 52 m³Initial Pressure (P₁) = 760 cm Hg

Final Pressure (P₂) = 104 cm Hg

Boyle’s Law: P₁V₁ = P₂V₂

V₂ = 760 × 52 ÷ 104 = 380 m³

So, the volume of the gas at a pressure of 104 cm Hg, with temperature remaining constant, is 380 m³.

OR

Pressure (P) = 4 atm

Volume (V) = ?

Gas Constant (R) = 0.082 L atm mol^-1 K^-1

Temperature (T) = 300 K

No of mole (n) = 8/2 = 4 mol

We know, PV = nRT

or, V = nRT/P = 4 × 0.082 × 300 / 4 = 24.6 liters

So, the volume of 8 g of H₂ gas at the given conditions is 24.6 litres.

The refractive index of a medium (n) is inversely related to the velocity of light (v) in that medium. It is given by:n = c/v

OR

Concave mirrors are used in the headlights of cars to produce a parallel beam of light covering a longer distance on the road.

Two advantages of using a CFL (Compact Fluorescent Lamp) over an incandescent lamp are:

1. Energy Efficiency: CFLs use less electricity.
2. Longer Lifespan: CFLs last much longer.

An aqueous solution of sugar cannot conduct electricity because sugar does not dissociate into ions in water. While, sodium chloride (NaCl) dissociates into Na⁺ and Cl⁻ ions, which carry electric current.

OR

It is appropriate to use the term formula weight instead of molecular weight for sodium chloride (NaCl) because NaCl is an ionic compound, not a molecule. Formula weight refers to the sum of the atomic weights of the ions in the formula unit.

Hydrogen sulfide (H₂S) gas can be prepared in Kipp’s apparatus.Balanced Chemical Equation:

FeS + H₂SO₄ → FeSO₄ + H₂S ↑

In this reaction, iron(II) sulfide (FeS) reacts with sulfuric acid (H_₂SO_₄) to produce iron(II) sulfate (FeSO_₄) and hydrogen sulfide gas (H_₂S).

To obtain metallic zinc from zinc oxide, zinc oxide is reduced by carbon or carbon monoxide. The balanced chemical equation for the reduction of zinc oxide with carbon is:

ZnO + C → Zn + CO

OR

When a piece of zinc is added to an aqueous solution of CuSO₄, zinc displaces copper from the solution, resulting in the formation of zinc sulfate and metallic copper. The balanced chemical equation is:

Zn + CuSO₄​ → ZnSO₄​ + Cu

Electronic Theory Explanation:

Oxidation:

Zinc (Zn) loses electrons and is oxidized to Zn²⁺:

Zn → Zn ²⁺ + 2𝑒⁻

Reduction:

Copper ions (Cu²⁺) gain electrons and are reduced to metallic copper (Cu):

Cu²⁺ + 2e⁻ → Cu

Ethylene (C₂H₄) Structural Formula:

H₂​C=CH₂ ​

In ethylene, the two carbon atoms are connected by a double bond. The presence of the double bond indicates that ethylene is an unsaturated hydrocarbon.

OR

To prevent the usage of Ethanol as beverages, a small amount (approximately) of Methanol (CH₃OH) is added to it. This makes Ethanol unfit for drinking and is called denatured spirit.

Charle’s law: At constant pressure, the volume of a given mass of a gas increases or decreases by 1/273 of its volume at 0°C for each one-degree rise or fall in temperature.The mathematical form of Charle’s law:

V_t=Vo(1+t/273)

V_o = volume at 0°C

V_t = volume at t°C

Balanced chemical equation:(NH₄)_2​SO₄ + 2NaOH → 2NH₃  +Na₂​SO₄​ + 2H₂​O

Molecular mass of NH₃ = 17 g

Molecular mass of (NH₄)_2​SO₄

= [2 × (14 + 4)] + [32 + (4 × 16)]

= 132 g

From the balanced equation, 2 moles of NH₃ are produced from 1 mole of (NH₄)2 ​SO₄. Therefore, the moles of ammonium sulfate required to produce 0.4 moles of NH₃ are:

Moles of (NH₄)2 ​SO₄ = 0.4/2 = 0.2 mol

Mass of (NH₄)2SO₄ = 0.2  × 132 = 26.4 g

26.4 g of ammonium sulfate will be required to prepare 6.8 g of ammonia.

The volume expansion coefficient of a gas at constant pressure is the fractional change in volume per unit change in temperature.At 0°C (273 K), its value is approximately 0.00366 K⁻¹, meaning the gas volume increases by about 0.366% per 1°C increase in temperature at constant pressure.

OR

The two similarities between heat conduction and electrical conduction are

1. Both processes involve the transfer of energy.
2. Both require a medium for transfer.

Diamond is a non-metal with very high thermal conductivity.

The two laws of refraction of light:

1. The incident ray, the refracted ray and the normal at the point of incidence on the refracting surface lie in the same plane.
2. For a given pair of media and for a given colour of light, the sine of the angle of incidence bears a constant ratio to the sine of the angle of refraction.

Mathematical form of the second law

sin i/ sin r =constant

In an optical system, a ray close to and nearly parallel to the principal axis is known as a paraxial ray.

When a paraxial ray of light OA incidents on a concave of a very small aperture, then it gets reflected along AQ. If the principal focus and centre of curvature of the mirror be F and C respectively then AC being the radius of curvature will act as a normal to the reflecting surface at A.

Hence, at point A, the angle of incidence (i) is equal to the angle of reflection (r) and the reflected ray will meet the principal axis at the principal focus E ∴ OA || XY, AC is the transversal, ∠OAC = ∠FCA = i. Again, ∠FAC is also equal to i, hence ∠FCA =∠FAC ∴ FA = FC.

As the aperture of the mirror is very small and we are considering only the paraxial rays (very close to the principal axis) FA is nearly equal to FP Hence, FP = FC and hence CP = 2FP

∴ r = 2f

∴ radius of curvature of the mirror =2 × focal length of the mirror

OR

Let a ray of monochromatic light OP incidents at P on the refracting face AB at an angle of incidence i₁ and suffer refraction from air to glass, bend towards the normal making an angle of refraction equal to r₁ and finally travel along the path PQ inside the prism. Again the refracted ray PQ strikes the refracting surface AC of the prism at an angle of incidence r₂ and after suffering refraction from glass to air, it emerges out of the prism at an angle of emergence i₂.

Here, the angle between the direction of the incident ray and the emergent ray (∠LMQ) is called the angle of deviation (δ) of the ray of light after refraction through the prism and its value is

δ = ∠MPQ + ∠MQP = (i_₁– r₁)+(i₂ – r₂)

δ = (i_₁+ i₂) – (r₁ + r₂)  …(i)

Again, in the quadrilateral APNQ,

∠PAQ + ∠PNQ + 90° + 90° = 360°

or, A + ∠PNQ = 180° [where A = ∠PAQ]

∴ ∠PNQ=180° – A …(ii)

(ii) But in ΔPNQ,

r_₁ + r_₂ + ∠PNQ = 180°

or, ∠PNQ = 180° – (r_₁ + r_₂) …(ii)

From equation (ii) and (iii) we get,

A = r_₁ + r_₂  …(iv)

∴ From equation (i)and (iv) we get,

δ = i_₁+ i₂ – A (Hence Proved)

Faraday’s law of electromagnetic induction:

1. Whenever there is a change in magnetic flux linked with a coil, an emf is induced, which lasts as long as the change in magnetic flux is linked with the coil changes.
2. The magnitude of the induced emf is directly proportional to the rate of change magnitude flux linked with the coil.

Alternating Current: An alternating current can be defined as a current that changes its magnitude and polarity at regular intervals of time.

Resistance (R) = 440 ohmVoltage (V) = 220 V

Time (t) = 10 h

Calculation of power:

P = V^2\over R = 220^2\over440 = 110 watts

Calculation of Electrical Energy:

E = P × t

= 110 watts × 10 h

= 1100 Wh

= 1.1 BOT

OR

Initial length = l

Initial area = a

Initial Resistance (R) = ρ l\over a = 6 ohm

New length = 2 × l

New Area = a \over 2

Final Resistance (R’) = ρ 2 × l\over {a\over2} = 4 × ρ l\over a  = 4 × 6 ohm = 24 ohm

The final resistance of the stretched wire is 24 ohms.

Mass defect refers to the difference between the actual mass of an atomic nucleus and the sum of the masses of its constituent protons and neutrons, due to the conversion of mass into energy during nuclear binding.

The energy released in nuclear fusion comes from the conversion of mass into energy. When light nuclei (such as hydrogen isotopes) fuse to form a heavier nucleus (like helium), a small amount of mass is lost and converted into energy.

A periodic property is a characteristic of elements that repeats at regular intervals when elements are arranged by increasing atomic number. Example: Atomic radius decreases across a period and increases down a group.Mass number is not a periodic property, as it doesn’t follow a regular trend across the periodic table.

OR

Electronegativity is the ability of an atom to attract electrons towards itself in a chemical bond.

In Group 1 of the long periodic table, electronegativity decreases from top to bottom as the atomic size increases, making it harder for the nucleus to attract bonding electrons.

The energy responsible for the chemical reactions during electrolysis is electrical energy.At the Cathode (Reduction):

2H⁺ + 2e^– → H₂ (Hydrogen Gas)

Hydrogen ions gain electrons to form hydrogen gas.

At the Anode (Oxidation):

H₂O → O₂ + 4H⁺ + 4e^–

Water molecules lose electrons to form oxygen gas and hydrogen ions.

SO₃ (Contact Process):

2SO₂ (g) + O₂ (g) → 2SO₃ (g)

Conditions:

Catalyst: Vanadium pentoxide (V₂O₅)

Temperature: 450°C

Pressure: 1-2 atm

Preparation of H₂SO₄ from SO₃ :

Sulfur trioxide (SO₃) is absorbed in concentrated sulfuric acid (H₂SO₄) to form oleum (H₂S₂O₇) which is then diluted with water to form sulfuric acid.

2SO₃ (g) +  H₂SO₄ (l) → H₂S₂O₇ (Oleum)

H₂S₂O₇ (l) + H₂O (l)  → 2H₂SO₄ (l)

The addition of hydrogen to acetylene (ethyne) produces ethane. The reaction occurs in the presence of a nickel at 300° C.

C₂H₂ (g) + 2H₂ → C₂H₆ (g)

One Use of LPG:

LPG (Liquefied Petroleum Gas) is commonly used as a cooking fuel in households.

OR

Ethanol (CH₃CH₂OH) is converted to ethene (CH₂=CH₂) by dehydration using concentrated sulfuric acid as a catalyst at 170ºC.

CH₃CH₂OH → CH₂=CH₂ + H₂O

Biodegradation of Protein:

Proteins are biodegraded in nature by enzymes into amino acids, which are further broken down by bacteria into simpler compounds like carbon dioxide and water.

The main component of biogas is methane (CH₄), which typically makes up about 50-75% of the gas.

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

Solution

There are 8 elements in the third period of the long periodic table.

SolutionThe radioactive ray that is not made up of particles is gamma rays (γ-rays). Gamma rays are electromagnetic waves, not particles.

SolutionThe absolute scale of temperature is known as the Kelvin scale. On this scale, temperature is measured in Kelvin (K), and it starts from absolute zero, which is the theoretical lowest possible temperature where molecular motion ceases. Absolute zero is defined as 0 K, equivalent to -273.15°C.

The two advantages of AC over DC

1. AC is easier and cheaper to generate than DC.
2. Power loss in AC is less as compared to DC during transmission.

When ammonium hydroxide NH₄OH is treated with iron (III) chloride solution, it produces a reddish brown precipitate of ferric hydroxide Fe(OH)₃, which is insoluble in excess of NH₄Cl.

6NH₄OH + 2FeCl₃ → 2Fe(OH)₃ + 6NH₄Cl

When methane (CH₄) undergoes complete combustion in oxygen (O₂), it produces carbon dioxide (CO₂) and water (H₂O).  The balanced chemical equation for this reaction is:

CH₄ (g) + 2O₂ (g) → CO₂ (g)+ 2H₂O (l)