MADHYAMIK PARIKSHA (SE) - 2026
PHYSICAL SCIENCE (Model Question Paper Set-2)
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 The unit for measuring the thickness of the ozone layer is—
(a) Meter (b) Dobson (c) Hertz (d) Decibel
Answer: (b) Dobson (Dobson Unit)
1.2 What is the volume of 2 moles of an ideal gas at STP?
(a) 11.2 L (b) 22.4 L (c) 44.8 L (d) 2.24 L
Answer: (c) 44.8 L [ $2 \times 22.4 = 44.8 L$ ]
1.3 What is the value of '$a$' in the equation $PV=aRT$ for an ideal gas? (where $w$ = mass of gas, $M$ = molar mass)
(a) $M/w$ (b) $w/M$ (c) $wM$ (d) $M$
Answer: (b) $w/M$ [Since moles $n = \frac{w}{M}$]
1.4 The value of the mechanical equivalent of heat (J) in SI unit is—
(a) 4.2 J/cal (b) 1 J/J (c) 4.2
Answer: (b) 1 J/J [In SI, unit of both Heat and Work is Joule, so $J=1$]
1.5 Which mirror is used in the headlights of motor cars?
(a) Plane (b) Convex (c) Concave (d) Cylindrical
Answer: (c) Concave (Parabolic concave mirrors are ideal)
1.6 The formation of a rainbow is due to—
(a) Reflection (b) Refraction (c) Dispersion (d) Interference
Answer: (c) Dispersion of light
1.7 The charge of an electron is—
(a) $-1.6 \times 10^{-19} C$ (b) $1.6 \times 10^{19} C$ (c) $6.25 \times 10^{18} C$ (d) $9.1 \times 10^{-31} C$
Answer: (a) $-1.6 \times 10^{-19} C$
1.8 On which principle does the electric fuse wire work?
(a) Chemical effect of current (b) Magnetic effect of current (c) Heating effect of current (d) Electromagnetic induction
Answer: (c) Heating effect of current
1.9 The SI unit of radioactivity is—
(a) Curie (b) Rutherford (c) Becquerel (d) Roentgen
Answer: (c) Becquerel (Bq)
1.10 Which of the following is an alkaline earth metal?
(a) Na (b) K (c) Mg (d) Fe
Answer: (c) Mg (Magnesium)
1.11 Which compound contains a triple covalent bond?
(a) $CH_4$ (b) $C_2H_4$ (c) $N_2$ (d) $H_2O$
Answer: (c) $N_2$ (Nitrogen, $N \equiv N$)
1.12 In silver plating, the anode used is—
(a) Pure Silver plate (b) Impure Silver (c) Iron spoon (d) Graphite
Answer: (a) Pure Silver plate
1.13 The gas having the smell of rotten eggs is—
(a) $NH_3$ (b) $H_2S$ (c) $Cl_2$ (d) $SO_2$
Answer: (b) $H_2S$ (Hydrogen Sulphide)
1.14 Which is not an ore of Aluminum?
(a) Bauxite (b) Cryolite (c) Gibbsite (d) Calamine
Answer: (d) Calamine (It is an ore of Zinc)
1.15 The simplest Alkyne is—
(a) Methane (b) Ethane (c) Acetylene (d) Ethylene
Answer: (c) Acetylene ($C_2H_2$)
GROUP — B (Very Short Answer Questions)
2. Answer the following questions (Alternatives are to be noted): (1 × 21 = 21)
2.1 In which layer of the atmosphere are Auroras seen?
Answer: Ionosphere or Thermosphere.
2.2 Name an organic greenhouse gas.
Answer: Methane ($CH_4$).
OR, Write the SI unit of calorific value.
Answer: $kJ/kg$ or $MJ/kg$.
2.3 What is the value of absolute zero temperature on the Celsius scale?
Answer: $-273.15^\circ C$.
2.4 Write True or False: Real gases behave like ideal gases at high temperature and low pressure.
Answer: True.
2.5 What is the nature of the mirror used by dentists?
Answer: Concave mirror.
2.6 If the refractive index of glass with respect to air is 1.5, what is the refractive index of air with respect to glass?
Answer: $\frac{1}{1.5} = \frac{2}{3}$ or $0.67$.
2.7 1 BOT unit = how many Joules?
Answer: $3.6 \times 10^6$ Joules.
2.8 Which energy is converted to which energy in a Dynamo?
Answer: Mechanical energy is converted to Electrical energy.
2.9 Match the Left Column with the Right Column:
| 2.9.1 Coinage Metal | (d) Silver (Ag) |
| 2.9.2 Noble Gas | (a) Radon (Rn) |
| 2.9.3 Ore of Zinc | (b) Zinc Blende |
| 2.9.4 Rust | (c) Hydrated Ferric Oxide |
2.10 How many periods were there in Mendeleev's periodic table?
Answer: 7.
2.11 How is the speed of reaction of covalent compounds?
Answer: Slow.
2.12 In which unit is the electric current measured during electrolysis?
Answer: Ampere.
2.13 Fill in the blank: ______ is used to dry $H_2S$ gas.
Answer: Phosphorus Pentoxide ($P_2O_5$).
OR, What is the percentage of $H_2SO_4$ in Oleum?
Answer: More than 100% (due to dissolved $SO_3$).
2.14 Which metal is present in Stainless Steel other than Iron?
Answer: Chromium ($Cr$) and Nickel ($Ni$).
2.15 What is the full name of PVC?
Answer: Poly Vinyl Chloride.
2.16 Name the first organic compound prepared in the laboratory.
Answer: Urea [$CO(NH_2)_2$].
OR, Name a biodegradable polymer.
Answer: Cellulose or Starch.
GROUP — C (Short Answer Questions)
3. Answer the following questions (Alternatives are to be noted): (2 × 9 = 18)
3.1 Write two harmful effects of ozone layer depletion on the environment.
Answer: 1. UV rays reach the earth causing skin cancer. 2. Photosynthesis is inhibited, reducing crop yield.
3.2 Define absolute zero temperature from Charles's law.
Answer: According to Charles's law, the temperature at which the volume of any gas theoretically becomes zero at constant pressure is called absolute zero temperature ($-273^\circ C$).
Mathematically, $V_t = V_0(1 + \frac{t}{273})$. If $t = -273$, then $V_t = 0$.
3.3 Define refractive index.
Answer: The ratio of the sine of the angle of incidence to the sine of the angle of refraction when light passes from one medium to another is called the refractive index of the second medium with respect to the first.
3.4 On what factors does the rotation of Barlow's Wheel depend?
Answer: 1. Strength of current (increases rotation). 2. Strength of magnetic field (increases rotation). 3. Direction of rotation reverses if current direction or magnetic poles are reversed.
3.5 Write two differences between electrovalent and covalent compounds.
Answer: 1. Electrovalent compounds have high melting/boiling points; covalent ones have low. 2. Electrovalent compounds are generally soluble in water; covalent ones are soluble in organic solvents.
3.6 What is electroplating? What is its purpose?
Answer: The process of coating a base metal with a layer of a more noble metal using electrolysis is called electroplating. Purpose: 1. To prevent corrosion (rusting). 2. For decoration.
3.7 Write the names of chemicals and the equation for the laboratory preparation of $H_2S$.
Answer: Chemicals: Ferrous Sulphide ($FeS$) and dilute Sulphuric Acid ($H_2SO_4$).
Equation: $FeS + H_2SO_4 \rightarrow FeSO_4 + H_2S \uparrow$.
3.8 What is Thermite Welding?
Answer: A mixture of $Fe_2O_3$ and $Al$ powder (3:1) is ignited to produce molten iron. This molten iron is used to join railway tracks or broken machinery. This process is called thermite welding.
3.9 What is Denatured Spirit? State its use.
Answer: Rectified spirit is made unfit for drinking by adding poisonous substances like Methanol (10%), Pyridine, or Naphtha. This is called Denatured or Methylated Spirit. Use: It is used as a solvent in varnishes and as fuel.
GROUP — D (Long Answer Questions)
4. Answer the following questions (Alternatives are to be noted): (3 × 12 = 36)
4.1 State Boyle's law and explain why Boyle's law is violated while inflating a balloon.
Answer: Law: At constant temperature, the volume of a fixed mass of gas is inversely proportional to its pressure ($V \propto \frac{1}{P}$).
Explanation: While inflating a balloon, we add air, thus increasing the mass of the gas. Boyle's law applies only to a "fixed mass" of gas. Since mass changes here, the law is not applicable.
4.2 Define Thermal Conductivity. Write its SI unit. What is thermal resistance?
Answer: It is the amount of heat flowing normally per second through a unit area of a slab of unit thickness when the temperature difference between opposite faces is 1 degree. Unit: $W \cdot m^{-1} \cdot K^{-1}$.
Thermal Resistance: The property of a material to obstruct the flow of heat ($R_{th} = \frac{d}{KA}$).
4.3 Show that there is no angular deviation of a light ray passing through a rectangular glass slab, only lateral displacement occurs.
Answer: (Geometric proof required showing emergent ray is parallel to incident ray, i.e., $\angle i_1 = \angle i_2$, hence deviation $\delta = 0$).
4.4 What is meant by accommodation of the eye? What is the cause of long-sightedness?
Answer: The ability of the eye lens to adjust its focal length to focus on near or distant objects clearly is called accommodation. Cause of Hypermetropia: Shortening of the eyeball or increase in the focal length of the lens.
4.5 Define resistance from Ohm's Law. Calculate the equivalent resistance of three resistors $R_1, R_2, R_3$ connected in series.
Answer: Definition: The ratio of potential difference ($V$) to current ($I$) is resistance ($R=V/I$).
Equivalent Resistance: $R_s = R_1 + R_2 + R_3$ (Proof required).
OR, Write the characteristics of a fuse wire. What is meant by 1 kWh?
Answer: Fuse characteristics: High resistance and low melting point. 1 kWh is the electrical energy consumed by a device of 1 kilowatt power in 1 hour ($3.6 \times 10^6 J$).
4.6 Compare Alpha, Beta, and Gamma rays with respect to penetrating power and charge.
Answer:
Penetrating Power: $\gamma > \beta > \alpha$.
Charge: $\alpha$ (Positive, +2), $\beta$ (Negative, -1), $\gamma$ (Neutral, 0).
4.7 Why is Hydrogen called a 'Rogue Element'? Explain the oxidizing trend of halogens.
Answer: Hydrogen resembles both Alkali metals (Group 1) and Halogens (Group 17), creating confusion in its position, hence called a 'Rogue Element'. Oxidizing power of halogens decreases down the group ($F > Cl > Br > I$).
4.8 Write the principle and equation for the preparation of Nitric Acid by Ostwald's process.
Answer: Principle: Ammonia is oxidized by atmospheric oxygen in the presence of $Pt-Rh$ gauze catalyst at $800^\circ C$ to form Nitric Oxide ($NO$), which is further oxidized and dissolved in water to form $HNO_3$.
Equation: $4NH_3 + 5O_2 \xrightarrow{Pt, 800^\circ C} 4NO + 6H_2O$ (1st step).
4.9 Write three main differences between organic and inorganic compounds. What is Catenation?
Answer: Differences: 1. Carbon is essential (Organic) vs Non-essential (Inorganic). 2. Covalent bonds (Organic) vs Ionic bonds (Inorganic). 3. Low MP/BP (Organic) vs High MP/BP (Inorganic).
Catenation: The property of carbon atoms to link with one another to form long chains.
4.10 What is a substitution reaction? Write the steps for the reaction of Methane with Chlorine (in diffused sunlight).
Answer: A reaction where an atom/group in a molecule is replaced by another atom. Reaction: $CH_4 + Cl_2 \rightarrow CH_3Cl + HCl$. Further substitution gives $CH_2Cl_2, CHCl_3, CCl_4$.
4.11 What are the conditions for rusting of iron? Write two ways to prevent rusting.
Answer: Conditions: Presence of Water (moisture) and Oxygen. Prevention: 1. Galvanization (Zinc coating). 2. Painting or oiling.
4.12 Numerical: How many grams of $CO_2$ will be obtained by strongly heating 10g of Calcium Carbonate? (Ca=40, C=12, O=16).
Solution: Reaction: $CaCO_3 \rightarrow CaO + CO_2$.
Molar Mass: $CaCO_3 = 40+12+48 = 100$, $CO_2 = 12+32=44$.
100g $CaCO_3$ gives 44g $CO_2$.
10g $CaCO_3$ gives $\frac{44}{100} \times 10 = 4.4g$ $CO_2$.