Madhyamik 2026 Physical Science Suggestion (English version) Set-1

MADHYAMIK PARIKSHA (SE) - 2026

PHYSICAL SCIENCE (Model Question Paper & Solution)

Time: 3 Hours 15 Minutes | Full Marks: 90

GROUP — A (Multiple Choice Questions)

1. Write the correct answer from the given alternatives: (1 × 15 = 15)

1.1 Which of the following is not a greenhouse gas?
(a) Methane (b) Water vapor (c) Nitrogen (d) Carbon dioxide
Answer: (c) Nitrogen ($N_2$)

1.2 According to Boyle's law, the PV vs P graph is—
(a) Straight line passing through origin (b) Parallel to P-axis (c) Parallel to V-axis (d) Rectangular hyperbola
Answer: (b) Parallel to P-axis

1.3 What is the vapour density of 1 mole of $CO_2$?
(a) 22 (b) 44 (c) 11 (d) 88
Answer: (a) 22 [Since $D = \frac{M}{2} = \frac{44}{2} = 22$]

1.4 The dimensional formula of thermal conductivity is—
(a) $MLT^{-3}K^{-1}$ (b) $MLT^{-2}K^{-1}$ (c) $ML^2T^{-3}K^{-1}$ (d) $MLT^{-3}K$
Answer: (a) $MLT^{-3}K^{-1}$

1.5 Which type of mirror is used by dentists?
(a) Convex mirror (b) Concave mirror (c) Plane mirror (d) Cylindrical mirror
Answer: (b) Concave mirror

1.6 In refraction of light, the deviation is minimum when the angle of incidence is—
(a) $0^\circ$ (b) $45^\circ$ (c) $60^\circ$ (d) $90^\circ$
Answer: (a) $0^\circ$

1.7 Coulomb's law is applicable for—
(a) Only static charges (b) Only moving charges (c) Static and point charges (d) Any charges
Answer: (c) Static and point charges

1.8 Resistivity of which material decreases with the increase in temperature?
(a) Copper (b) Iron (c) Germanium (d) Nichrome
Answer: (c) Germanium (Semiconductor)

1.9 If an alpha particle is emitted from a radioactive element, the mass number of the new element—
(a) Decreases by 2 (b) Decreases by 4 (c) Increases by 2 (d) Increases by 4
Answer: (b) Decreases by 4

1.10 In the periodic table, halogens are placed in—
(a) Group 1 (b) Group 2 (c) Group 17 (d) Group 18
Answer: (c) Group 17

1.11 Molecule does not exist for which of the following compounds?
(a) Sugar (b) Glucose (c) Sodium Chloride (d) Water
Answer: (c) Sodium Chloride (Ionic compound)

1.12 In the purification of copper, the anode used is—
(a) Pure copper plate (b) Impure copper rod (c) Graphite rod (d) Platinum wire
Answer: (b) Impure copper rod

1.13 The catalyst used in the Contact process for the preparation of $H_2SO_4$ is—
(a) Fe powder (b) Pt powder (c) $V_2O_5$ (d) NO
Answer: (c) $V_2O_5$ (Vanadium Pentoxide)

1.14 The Thermite mixture is—
(a) $Fe_2O_3 + Al$ (b) $Fe_2O_3 + Cu$ (c) $ZnO + C$ (d) $CuO + H_2$
Answer: (a) $Fe_2O_3 + Al$

1.15 The functional group of vinegar is—
(a) $-OH$ (b) $-CHO$ (c) $-COOH$ (d) $>C=O$
Answer: (c) $-COOH$

GROUP — B (Very Short Answer Questions)

2. Answer the following questions (Alternatives are to be noted): (1 × 21 = 21)

2.1 Name the coldest layer of the atmosphere.
Answer: Mesosphere.

2.2 Which gas trapped in coal mines is used as fuel?
Answer: Methane ($CH_4$).
OR, What is Methane Hydrate?
Answer: It is a crystalline solid resembling ice with the formula $4CH_4 \cdot 23H_2O$, where methane molecules are trapped in a lattice of water molecules.

2.3 What are the constants in Charles's law?
Answer: Mass of the gas and Pressure of the gas.

2.4 State True or False: Equal volumes of all gases under the same temperature and pressure contain equal number of molecules.
Answer: True (Avogadro's Law).

2.5 What is the deviation of a light ray passing through the optical center of a lens?
Answer: $0^\circ$ (Zero degree).

2.6 Which color of white light bends the most during dispersion through a prism?
Answer: Violet.

2.7 Does Fleming's Left Hand Rule represent the principle of a motor or a generator?
Answer: Motor.

2.8 What should be the resistance of an ideal voltmeter?
Answer: Infinite.

2.9 Match the Left Column with the Right Column:

2.9.1 Transuranic element	(d) Plutonium
2.9.2 Ore of Aluminum	(a) Bauxite
2.9.3 Detected by Nessler's Reagent	(b) $NH_3$
2.9.4 An unsaturated hydrocarbon	(c) Ethylene

2.10 Show the Lewis dot structure of the Fluorine molecule ($F_2$).
Answer: $: \ddot{F} \cdot + \cdot \ddot{F} : \longrightarrow : \ddot{F} - \ddot{F} :$

2.11 What electrolyte is used for gold plating?
Answer: Potassium Aurocyanide [$KAu(CN)_2$] solution.

2.12 Fill in the blanks: ______ metal is found in anode mud.
Answer: Gold (Au) / Platinum (Pt).

2.13 Write one difference between Liquor Ammonia and Liquid Ammonia.
Answer: Liquor ammonia is a concentrated aqueous solution of ammonia, while liquid ammonia is pure ammonia gas liquefied under pressure.
OR, What is Nitrolim?
Answer: It is a mixture of Calcium Cyanamide ($CaCN_2$) and Carbon ($C$), used as fertilizer.

2.14 Which is the common element in Bronze and Brass?
Answer: Copper ($Cu$).

2.15 Which gas is produced by the dehydration of Ethyl Alcohol?
Answer: Ethylene ($C_2H_4$).

2.16 Write the name of the monomer of Teflon.
Answer: Tetrafluoroethylene ($C_2F_4$).
OR, Which gas burns in a carbide lamp?
Answer: Acetylene ($C_2H_2$).

GROUP — C (Short Answer Questions)

3. Answer the following questions (Alternatives are to be noted): (2 × 9 = 18)

3.1 Why is Methane Hydrate called 'Fire Ice'?
Answer: Methane hydrate looks like white ice crystals. However, since the trapped methane is highly flammable, it burns when brought near a flame. As it looks like ice but catches fire, it is called 'Fire Ice'.

3.2 The pressure of a fixed mass of gas at $0^\circ C$ is doubled and its volume is halved. What will be the final temperature?
Solution: Let initial Pressure $P_1 = P$, Volume $V_1 = V$, Temp $T_1 = 273 K$.
Final Pressure $P_2 = 2P$, Volume $V_2 = \frac{V}{2}$.
Using Combined Gas Law: $\frac{P_1V_1}{T_1} = \frac{P_2V_2}{T_2}$
$\frac{PV}{273} = \frac{2P \times \frac{V}{2}}{T_2}$
$\frac{PV}{273} = \frac{PV}{T_2}$
$\therefore T_2 = 273 K$. So, the final temperature remains $0^\circ C$ (unchanged).

3.3 How can a real and magnified image be formed by a convex lens? Draw a ray diagram.
Answer: When an object is placed between the Focus ($F$) and twice the focal length ($2F$) of a convex lens, a real, inverted, and magnified image is formed beyond $2F$. (Diagram to be drawn).
OR, State the second law of refraction of light.
Answer: 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 for a light of given color. $\frac{\sin i}{\sin r} = \mu$ (constant).

3.4 State the relation between resistance and cross-sectional area of a conductor.
Answer: At constant temperature and material, Resistance ($R$) is inversely proportional to the cross-sectional area ($A$) of the conductor. i.e., $R \propto \frac{1}{A}$.

3.5 Why is the melting point of NaCl higher than that of Glucose?
Answer: NaCl is an ionic compound held together by strong electrostatic forces between ions, requiring high energy to break. Glucose is a covalent compound with weak intermolecular forces, requiring less energy to melt. Hence, NaCl has a higher melting point.

3.6 Write the cathode and anode reactions for the electrolysis of acidulated water.
Answer:
Cathode: $2H^+ + 2e^- \rightarrow H_2 \uparrow$
Anode: $4OH^- - 4e^- \rightarrow 2H_2O + O_2 \uparrow$

3.7 Why is quicklime (CaO) used to dry ammonia gas instead of conc. $H_2SO_4$?
Answer: Ammonia is basic in nature. If acidic drying agents like $H_2SO_4$ or $P_2O_5$ are used, they react with ammonia to form salts. CaO being basic does not react with Ammonia but selectively absorbs moisture.

3.8 What is the advantage of using alloys? Write the composition of Duralumin.
Answer: Alloys are harder, more durable, and resistant to corrosion compared to pure metals. Composition of Duralumin: $Al (95\%) + Cu (4\%) + Mg + Mn$.

3.9 Define functional group. Give an example.
Answer: An atom or group of atoms present in an organic molecule that determines its chemical properties is called a functional group. Example: $-OH$ group in Alcohol.

GROUP — D (Long Answer Questions)

4. Answer the following questions (Alternatives are to be noted): (3 × 12 = 36)

4.1 Establish the combined gas law equation from Boyle's Law and Charles's Law.
Answer:
Boyle's Law: $V \propto \frac{1}{P}$ (when $T$ is constant).
Charles's Law: $V \propto T$ (when $P$ is constant).
Combining both: $V \propto \frac{T}{P}$ or $PV \propto T$.
$\therefore PV = KT$. For 1 mole of gas, $K=R$.
Thus, $PV = nRT$ (Ideal Gas Equation).

4.2 Write the relation between the coefficient of real expansion and apparent expansion of a liquid. What is the value of volume expansion coefficient for gases?
Answer: Relation: $\gamma_r = \gamma_a + \gamma_g$ (Real expansion coeff. = Apparent expansion coeff. + Volume expansion coeff. of the container).
Value for gases: $\gamma_p = \frac{1}{273} {^\circ}C^{-1}$.

4.3 Prove that for a prism, $\delta = i_1 + i_2 - A$.
Answer: It can be proved geometrically that the angle of deviation is equal to the sum of the angle of incidence and angle of emergence minus the angle of the prism. (Standard geometric proof required).
OR, What is Hypermetropia? How is it corrected?
Answer: Long-sightedness (can see far objects clearly, but near objects are blurry) is called Hypermetropia. It is corrected using a Convex Lens.

4.4 State Rayleigh's law of scattering. Why does the sky appear blue?
Answer: Rayleigh's law: Intensity of scattered light $I \propto \frac{1}{\lambda^4}$.
Blue light has a shorter wavelength ($\lambda$) compared to red. So, it is scattered most by atmospheric particles. This scattered blue light reaches our eyes, making the sky appear blue.

4.5 State Joule's laws of heating effect of current.
Answer:
1. $H \propto I^2$ (when $R, t$ constant).
2. $H \propto R$ (when $I, t$ constant).
3. $H \propto t$ (when $I, R$ constant).
OR, Two resistors are in parallel. Equivalent resistance is 2.4 $\Omega$. If one is 4 $\Omega$, find the other.
Solution: $\frac{1}{R_p} = \frac{1}{R_1} + \frac{1}{R_2}$
$\frac{1}{2.4} = \frac{1}{4} + \frac{1}{R_2}$
$\frac{1}{R_2} = \frac{10}{24} - \frac{1}{4} = \frac{4}{24} = \frac{1}{6}$
$\therefore R_2 = 6 \Omega$.

4.6 State Lenz's law. Does it obey the law of conservation of energy?
Answer: Lenz's law states that the direction of induced current is such that it opposes the cause producing it. Yes, it obeys the law of conservation of energy because the mechanical work done against this opposing force is transformed into electrical energy.

4.7 Differentiate between Nuclear Fission and Fusion. What is the source of the Sun's energy?
Answer: Fission splits a heavy nucleus into lighter ones, while Fusion combines light nuclei into a heavier one. Fusion releases more energy than Fission. Source of Sun's energy: Nuclear Fusion.

4.8 State Mendeleev's Periodic Law. Which elements are called transition elements?
Answer: The physical and chemical properties of elements are periodic functions of their atomic weights. Elements having partially filled $d$-orbitals (Groups 3-12) are called transition elements (e.g., $Fe, Cu$).

4.9 Write the principle and conditions for the manufacture of Ammonia by Haber's Process.
Answer: Principle: $N_2 + 3H_2 \rightleftharpoons 2NH_3 + \text{Heat}$.
Conditions: 200 atm pressure, $450^\circ-550^\circ C$ temperature, and $Fe$ powder as catalyst with $Mo$ promoter.

4.10 What is meant by Carbon Reduction method? Give an example.
Answer: The process of extracting metals by reducing their oxides with Carbon (Coke) at high temperatures is called Carbon Reduction.
Example: $ZnO + C \xrightarrow{\Delta} Zn + CO \uparrow$.

4.11 How is Polythene prepared from Ethylene?
Answer: Polythene is prepared by the polymerization of Ethylene ($C_2H_4$) at high temperature and pressure in the presence of a catalyst.
OR, Write the reaction of Acetylene with Hydrogen. IUPAC name of $CH_3-CH(OH)-CH_3$.
Answer: Reaction: $HC \equiv CH + 2H_2 \xrightarrow{Ni/Pt} H_3C-CH_3$ (Ethane).
IUPAC Name: Propan-2-ol.

4.12 24g of Magnesium is burnt completely in Oxygen. Calculate the mass of Magnesium Oxide formed. (Mg=24, O=16).
Solution: Reaction: $2Mg + O_2 \rightarrow 2MgO$
Mass ratio: $2(24) \rightarrow 2(24+16)$
$48 \text{ g } Mg \rightarrow 80 \text{ g } MgO$
$1 \text{ g } Mg \rightarrow \frac{80}{48} \text{ g } MgO$
$24 \text{ g } Mg \rightarrow \frac{80}{48} \times 24 = 40 \text{ g } MgO$.
Answer: 40g of MgO is formed.