MADHYAMIK PARIKSHA (SE) - 2026
PHYSICAL SCIENCE (Model Question Paper Set-3)
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 non-conventional energy source?
(a) Solar energy (b) Wind energy (c) Tidal energy (d) Petroleum
Answer: (d) Petroleum
1.2 The average kinetic energy of gas molecules is ______ to its absolute temperature.
(a) Directly proportional (b) Inversely proportional (c) Proportional to square (d) Proportional to square root
Answer: (a) Directly proportional ($E \propto T$)
1.3 If the mass of $11.2$ liters of a gas at STP is $22$ grams, the gas could be—
(a) $CO$ (b) $CO_2$ (c) $NO_2$ (d) $SO_2$
Answer: (b) $CO_2$ [ $11.2L = 22g \Rightarrow 22.4L = 44g$, Molar mass of $CO_2$ is 44 ]
1.4 The relation between coefficient of linear expansion ($\alpha$), superficial expansion ($\beta$), and volume expansion ($\gamma$) of a solid is—
(a) $\alpha = \beta = \gamma$ (b) $6\alpha = 3\beta = 2\gamma$ (c) $\alpha = 2\beta = 3\gamma$ (d) $\alpha = \beta/2 = \gamma/3$
Answer: (b) $6\alpha = 3\beta = 2\gamma$ (or $\frac{\alpha}{1} = \frac{\beta}{2} = \frac{\gamma}{3}$)
1.5 The relation between refractive index ($\mu$) of a medium and wavelength of light ($\lambda$) is—
(a) $\mu \propto \lambda$ (b) $\mu \propto \frac{1}{\lambda}$ (c) $\mu \propto \lambda^2$ (d) $\mu \propto \frac{1}{\lambda^2}$
Answer: (d) $\mu \propto \frac{1}{\lambda^2}$ (According to Cauchy's equation)
1.6 Which mirror always forms a virtual, erect, and diminished image for all positions of the object?
(a) Convex mirror (b) Concave mirror (c) Plane mirror (d) None of these
Answer: (a) Convex mirror
1.7 The relation between potential difference ($V$), current ($I$), and resistance ($R$) is—
(a) $V = IR$ (b) $I = VR$ (c) $R = VI$ (d) $V = I^2R$
Answer: (a) $V = IR$ (Ohm's Law)
1.8 The practical unit of electric power is—
(a) Joule (b) Watt (c) Coulomb (d) Volt
Answer: (b) Watt
1.9 Which of the following rays has the highest ionizing power?
(a) $\alpha$-rays (b) $\beta$-rays (c) $\gamma$-rays (d) X-rays
Answer: (a) $\alpha$-rays
1.10 Which of the following elements has the highest electronegativity?
(a) O (b) N (c) F (d) Cl
Answer: (c) F (Fluorine)
1.11 Which of the following does not conduct electricity in molten state?
(a) $NaCl$ (b) $MgCl_2$ (c) $CCl_4$ (d) $KCl$
Answer: (c) $CCl_4$ (Carbon tetrachloride - Covalent compound)
1.12 The electrolyte used in Nickel plating is—
(a) Nickel sulphate and boric acid (b) Nickel chloride (c) Copper sulphate (d) Potassium argento cyanide
Answer: (a) Nickel sulphate and a small amount of boric acid
1.13 Which acid is identified by the Ring Test?
(a) $H_2SO_4$ (b) $HNO_3$ (c) $HCl$ (d) $CH_3COOH$
Answer: (b) $HNO_3$ (Nitric Acid)
1.14 Red Hematite is an ore of which metal?
(a) Copper (b) Iron (c) Aluminum (d) Zinc
Answer: (b) Iron
1.15 The general formula of Alkenes is—
(a) $C_nH_{2n+2}$ (b) $C_nH_{2n}$ (c) $C_nH_{2n-2}$ (d) $C_nH_{2n+1}$
Answer: (b) $C_nH_{2n}$
GROUP — B (Very Short Answer Questions)
2. Answer the following questions (Alternatives are to be noted): (1 × 21 = 21)
2.1 Name the compound mainly responsible for ozone layer depletion.
Answer: Chlorofluorocarbon ($CFC$).
2.2 What is Sweet Gas?
Answer: Coal Bed Methane ($CBM$) is called Sweet Gas.
OR, Which bacteria converts biomass into methane in a biogas plant?
Answer: Methanogenic bacteria.
2.3 What is the value of the universal gas constant $R$ in SI unit?
Answer: $8.314 \ J \cdot mol^{-1} \cdot K^{-1}$.
2.4 Write True or False: Liquids do not have their own coefficient of linear or superficial expansion.
Answer: True (Liquids only have volume expansion).
2.5 What is the angle of refraction when the angle of incidence is equal to the critical angle?
Answer: $90^\circ$.
2.6 Which type of lens is used in a camera?
Answer: Convex lens.
2.7 What is the color of the live wire in a household electric circuit (as per new convention)?
Answer: Brown.
2.8 What is used as a moderator in a nuclear reactor?
Answer: Heavy water ($D_2O$) or Graphite.
2.9 Match the Left Column with the Right Column:
| 2.9.1 Chalcogen element | (d) Sulfur (S) |
| 2.9.2 Manufacturing aircraft frames | (a) Duralumin |
| 2.9.3 Vinegar | (b) Acetic Acid |
| 2.9.4 Catenation property | (c) Carbon |
2.10 In which group are inert gases placed in the modified Mendeleev's periodic table?
Answer: Zero Group or Group 18 (Modern).
2.11 What is the shape of an Ammonia molecule?
Answer: Pyramidal.
2.12 What should be used as the cathode for copper plating on an iron spoon?
Answer: Iron spoon.
2.13 Fill in the blank: The boiling point of liquid hydrogen is _______.
Answer: $-252.8^\circ C$ (approx).
OR, What color precipitate is formed when Ammonia reacts with Nessler's reagent?
Answer: Brown.
2.14 Which metal is present in Brass besides Copper?
Answer: Zinc ($Zn$).
2.15 Write the IUPAC name of Ethyl Alcohol.
Answer: Ethanol.
2.16 Name the simplest ketone.
Answer: Acetone or Propanone.
OR, What is the main component of LPG?
Answer: Butane.
GROUP — C (Short Answer Questions)
3. Answer the following questions (Alternatives are to be noted): (2 × 9 = 18)
3.1 What is meant by Sustainable Development?
Answer: Sustainable development is the development that meets the needs of the present without compromising the ability of future generations to meet their own needs.
3.2 The volume of a fixed mass of gas at STP is $52m^3$. What will be its volume at the same temperature and a pressure of $104 \ cm \ Hg$?
Solution: $P_1 = 76 \ cm, V_1 = 52, P_2 = 104 \ cm$.
By Boyle's Law: $P_1V_1 = P_2V_2 \Rightarrow 76 \times 52 = 104 \times V_2 \Rightarrow V_2 = \frac{76 \times 52}{104} = 38 \ m^3$.
3.3 Why is red light used for danger signals?
Answer: Red light has the longest wavelength. According to Rayleigh's law of scattering ($I \propto 1/\lambda^4$), red light is scattered the least by atmospheric particles and can be seen from a long distance.
3.4 Why are household electrical appliances connected in parallel?
Answer: 1. Each appliance gets the full voltage (220V). 2. If one appliance fails or is switched off, others continue to work.
3.5 Draw the Lewis dot structure of Methane ($CH_4$).
Answer: Carbon shares its 4 valence electrons with 1 electron from each of the 4 Hydrogen atoms to form 4 single covalent bonds. (Diagram required).
3.6 Write two differences between metallic conductors and electrolytes.
Answer: 1. In metallic conductors, current flows via electrons; in electrolytes, it flows via ions. 2. Metallic conduction involves no chemical change; electrolysis involves chemical decomposition.
3.7 How is Urea prepared in industry? Give equation.
Answer: Liquid $CO_2$ and liquid Ammonia react in a closed vessel at $170^\circ-190^\circ C$ and $150-200$ atm pressure to form Urea.
Equation: $2NH_3 + CO_2 \rightarrow NH_2-CO-NH_2 + H_2O$.
3.8 What is Galvanization? Why is it done?
Answer: The process of coating iron or steel objects with a layer of zinc is called galvanization. It is done to prevent rusting.
3.9 Write the polymerization reaction of Ethylene. Write one use of Polythene.
Answer: At high temperature and pressure, Ethylene ($nC_2H_4$) molecules join to form Polythene ($-[-CH_2-CH_2-]_n-$). Use: Making carry bags, bottles.
GROUP — D (Long Answer Questions)
4. Answer the following questions (Alternatives are to be noted): (3 × 12 = 36)
4.1 Write the postulates of the Kinetic Theory of Gases (any three).
Answer: 1. Gases consist of tiny particles called molecules. 2. Molecules are point masses; their volume is negligible compared to the container's volume. 3. There are no forces of attraction or repulsion between gas molecules.
4.2 What is meant by thermal expansion of solids? Define coefficient of linear expansion.
Answer: The increase in shape and volume of a solid upon heating is called thermal expansion.
Definition: The increase in length per unit original length per degree rise in temperature is called the coefficient of linear expansion.
4.3 Explain the cause of dispersion of white light through a prism. Differentiate between pure and impure spectrum.
Answer: The refractive index of the prism material is different for different colors of light (highest for violet, lowest for red). So, different colors bend at different angles and get separated.
Difference: In a pure spectrum, colors do not overlap; in an impure spectrum, colors overlap each other.
4.4 The length of an object is 5 cm. If placed 20 cm in front of a convex lens, an image of 10 cm length is formed. Calculate linear magnification and image distance.
Solution: Object height $h_1=5$, Image height $h_2=10$.
Magnification $m = \frac{h_2}{h_1} = \frac{10}{5} = 2$.
Also, $m = \frac{v}{u} \Rightarrow 2 = \frac{v}{20} \Rightarrow v = 40 \ cm$.
Answer: Magnification 2, Image distance 40 cm.
4.5 Derive the relation $H= \frac{I^2Rt}{J}$ from Joule's Law. Why is Nichrome wire used in electric heaters?
Answer: From Joule's laws: $H \propto I^2$, $H \propto R$, $H \propto t$. Combining these, $H \propto I^2Rt$ or $H = \frac{I^2Rt}{J}$ ($J$ = Mechanical equivalent of heat).
Nichrome has high resistivity and high melting point, and it does not oxidize easily at high temperatures.
4.6 State Fleming's Left Hand Rule. Will Barlow's Wheel rotate with AC?
Answer: Rule: Stretch the forefinger, middle finger, and thumb of the left hand mutually perpendicular. If the forefinger points to the magnetic field and middle finger to current, the thumb points to the direction of motion.
No, Barlow's wheel will not rotate with AC (force direction reverses every half cycle).
4.7 What is Mass Defect? What is meant by Nuclear Binding Energy?
Answer: Mass Defect: The difference between the actual mass of a nucleus and the sum of masses of its constituent protons and neutrons.
Binding Energy: The energy equivalent to the mass defect that holds the nucleons together in the nucleus.
4.8 How do atomic radius and ionization potential vary along a period and a group in the periodic table?
Answer:
Along a period (Left to Right): Radius decreases, Ionization potential increases.
Down a group (Top to Bottom): Radius increases, Ionization potential decreases.
4.9 Write the reactions with conditions for the manufacture of Sulphuric Acid by Contact Process.
Answer: 1. $S + O_2 \rightarrow SO_2$.
2. $2SO_2 + O_2 \rightleftharpoons 2SO_3$ (Catalyst $V_2O_5$, $450^\circ C$).
3. $SO_3 + H_2SO_4 \rightarrow H_2S_2O_7$ (Oleum).
4. $H_2S_2O_7 + H_2O \rightarrow 2H_2SO_4$.
4.10 Mention the addition reaction of Hydrogen with Acetylene. What happens when Acetylene gas is passed through Bromine water?
Answer: Addition: Acetylene reacts with Hydrogen in presence of Ni/Pd catalyst to form Ethylene, then Ethane.
Bromine Water: If Acetylene is passed through reddish-brown bromine water, it becomes colorless, forming Tetrabromoethane. This proves unsaturation.
4.11 Name one ore of Copper and Zinc with formula. Write uses of Brass.
Answer: Copper: Copper Pyrites ($CuFeS_2$). Zinc: Zinc Blende ($ZnS$).
Uses of Brass: Making utensils, statues, musical instruments, cartridges.
4.12 What happens when steam is passed over red-hot iron? Write with equation. How many grams of Hydrogen can be obtained from 2 moles of Iron in this reaction?
Answer: Reaction: $3Fe + 4H_2O \rightleftharpoons Fe_3O_4 + 4H_2$.
Calculation: 3 moles of $Fe$ produce 4 moles of $H_2$.
3 mol $Fe \rightarrow 4 \times 2 = 8$g $H_2$.
2 mol $Fe \rightarrow \frac{8}{3} \times 2 = \frac{16}{3} = 5.33$g $H_2$.