SCIENCE – Code no. 086
SAMPLE QUESTION PAPER*
CLASS – X (2025-26)
General Instructions:
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(i)This question paper consists of 39 questions in 3 sections. Section A is Biology, Section B is Chemistry and Section C is Physics.
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(ii)All questions are compulsory. However, an internal choice is provided in some questions. A student is expected to attempt only one of these questions.
| Section – A | Marks | |
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| 1 | Identify the group of organisms that exhibit completely autotrophic mode of nutrition. | 1 |
| 2 | Which of the following cellular products are primarily generated during the anaerobic respiration process within yeast cells? | 1 |
| 3 | Which of the following is a correct combination of involuntary action and its primary control center in the brain? | 1 |
| 4 | A patient suffering from poor water retention and high urine frequency might be facing a condition due to the inadequate secretion of: | 1 |
| 5 | In a cross between tall pea plant (T) and dwarf pea plant (t), all F1 offspring were found to be tall. What can be inferred about the genetic cross configuration of the parent plants? | 1 |
| 6 |
Which are the correct statements related to the greenhouse effect and global warming?
(i)
Greenhouse gases trap infrared radiation reflected from the earth’s surface.
(ii)
Carbon dioxide is a primary contributor to the greenhouse effect.
(iii)
The greenhouse effect causes a reduction in global surface temperatures.
(iv)
Afforestation increases the atmospheric concentration of greenhouse gases.
(v)
Methane gas has a significantly higher warming potential than carbon dioxide.
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| 7 | Which of the following environmental conservation practices directly aids in maximizing the synthesis of biodegradable substances? | 1 |
| The following two questions consist of two statements – Assertion (A) and Reason (R). Answer these questions by selecting the appropriate option given below: | ||
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Assertion (A): The conversion of pyruvate into lactic acid takes place in human muscle cells during vigorous exercise. Reason (R): Anaerobic breakdown of glucose provides rapid energy production when there is a deficiency of oxygen. |
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| 9 |
Assertion (A): Phytoplankton will always have the least concentration of chemical toxins in an aquatic food chain. Reason (R): Biological magnification causes progressive accumulation of non-biodegradable pesticides at successive trophic levels. |
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| 10 | Unlike human beings, unicellular organisms like Amoeba do not possess specialized excretory organs or circulatory systems. Comment upon the statement with proper scientific justification. | 2 |
| 11 |
Students to attempt either option A or B.
A. What are the principal site and raw materials required for the process of photosynthesis in green plants? How do guard cells regulate the opening and closing of stomata for gaseous exchange?
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B. Explain the physiological mechanism by which oxygenated blood is distributed and deoxygenated blood is collected in the human circulatory system.
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| 12 | Around 50 hectares of wetland territory was designated as a Biosphere conservation zone. The following ecological organisms were found to be highly dominant in this Biosphere zone: | 2 |
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grass, deer, lion, phytoplanktons, zooplanktons, small fish, large fish, hawk, eagle, wolf, goat. Create a food web comprising two separate food chains with different environments (terrestrial and aquatic) by using the above data. |
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| 13 | Draw a neat labeled diagram of a human nephron and explain how the structural components assist in the filtration and selective reabsorption of urine. | 3 |
| 14 |
In a genetic hybrid cross experiment, plants with pure tall red flowers (TTRR) were crossed with plants with dwarf white flowers (ttrr). (i) Show the types of gametes formed when the F1 generation is self-pollinated.
(ii) A total of 400 plants were produced in the F2 generation which grew successfully. Show the phenotypic ratio and calculate the expected number of plants inheriting both dominant traits in these 400 saplings.
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| 15 |
Ananya consumed buttered toast and a glass of milk for her breakfast meal. Help her to understand the primary metabolic steps involved in the process of human nutrition by answering the questions given below. Attempt either subpart A or B.
A. Which of these consumed food components is exceptionally rich in complex carbohydrates (starch)? In which segment of the human alimentary canal is the breakdown of this component initiated? Name the enzyme, activation parameters, and associated salivary glands here.
OR
B. Which component of this breakfast menu contains high lipid/fat concentration? Explain how it is emulsified and digested.
C. Name the organ where protein digestion is completed and indicate the major enzyme secreted by the pancreas for protein degradation. D. The schematic vector figure given below represents various key organs of the human alimentary canal. Which of these labeled parts will possess the maximum density of villi structure to maximize absorption of digested nutrients as soon as digestion concludes? Figure: Human Alimentary Canal |
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For visually impaired students
D. How does the structure of villi enhance the functional capability of the small intestine?
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| 16 |
Attempt either option A or B.
A. Ramesh wanted to propagate rose plants in his botanical garden.
(i) Based on your knowledge of artificial vegetative propagation, which specific method should he adopt instead of using seeds? Justify your choice.
(ii) The plants produced via artificial vegetative methods show high genetic uniformity. Under what ecological conditions can a total lack of variation be disadvantageous to the plant population? Justify.
OR
B. Sarah was conducting an ecological study on the yield of tomato plants grown under varying environmental settings. She cultured 30 tomato plants inside both greenhouse X and greenhouse Y. She introduced honeybees as dynamic pollinators inside greenhouse X only.
(i) What fundamental difference will she observe in the net fruit production rate between the two greenhouses? Explain with biological reasoning.
(ii) List 3 structural transformations that characteristically occur in a typical angiosperm flower post-fertilization.
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| Section – B | Marks | |
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| 17 |
Which of the following chemical equations accurately represents a redox reaction, and what are the matching stoichiometric coefficients ‘p’ and ‘q’ to balance them?
Equation 1: Fe2O3(s) + p CO(g) → 2 Fe(s) + q CO2(g)
Equation 2: C3H8(g) + 5 O2(g) → p CO2(g) + q H2O(g) |
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| 18 |
Four comprehensive statements regarding the chemical reactions of different metal oxides with dilute nitric acid and aqueous potassium hydroxide are listed below:
I. Zinc oxide exhibits amphoteric behavior by reacting with both dilute nitric acid and aqueous potassium hydroxide.
II. Copper(II) oxide reacts readily with both dilute nitric acid and aqueous potassium hydroxide. III. Aluminium oxide behaves as an amphoteric oxide by reacting with both dilute nitric acid and aqueous potassium hydroxide. IV. Carbon dioxide does not undergo chemical neutralization with either dilute nitric acid or aqueous potassium hydroxide. Which statements are scientifically correct?
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| 19 | A strip of zinc metal is added to each of the two test tubes ‘X’ and ‘Y’ containing aqueous copper(II) sulphate and aqueous magnesium sulphate respectively. Which of the following observations is chemically correct? | 1 | |||||||||||||||
| 20 |
Phenolphthalein indicator is added separately to dilute sulphuric acid and to an aqueous solution of potassium hydroxide. What is the observed color of phenolphthalein in each solution?
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| 21 | Which of the following chemical substances, when dissolved in an equal volume of water, will produce the lowest pH value? | 1 | |||||||||||||||
| 22 | When dilute hydrochloric acid is added to solid sodium carbonate, a gas is evolved. When this gas is passed through lime water, it turns milky due to the formation of: | 1 | |||||||||||||||
| 23 | In a double displacement reaction between aqueous solutions of lead(II) nitrate and potassium iodide, the chemical formula of the insoluble precipitate formed is: | 1 | |||||||||||||||
| The following question consists of two statements – Assertion (A) and Reason (R). Answer these questions by selecting the appropriate option given below: | |||||||||||||||||
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C. Assertion (A) is true but Reason (R) is false. D. Assertion (A) is false but Reason (R) is true. |
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| 24 |
Assertion (A): C2H4, C3H6, and C4H8 belong to the same homologous series of alkenes. Reason (R): Members of a homologous series have successive molecular weights differing by exactly 14 units (-CH2 group). |
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| 25 |
The following laboratory activity is assembled in the chemistry lab by a teacher: A long copper rod is clamped on an iron support stand, and a small steel ball is attached to the free protruding tip of the rod using candle wax. The teacher then heats the copper rod steadily using a Bunsen burner at a middle point along its length. Students observe that after some time the wax melts and the steel ball drops down. A. If the teacher replaces the copper rod with a glass rod of matching dimensions, how will the timeline of the student’s observation change? Explain.
B. Does the copper rod undergo a change in its physical state during this process? Give a valid reason.
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| 26 |
Attempt either option A or B.
A. A highly reactive metal ‘M’ burns in air with a brilliant white flame and is extracted from its molten halide ore by electrolysis. It forms a crystalline basic oxide upon reacting with oxygen.
(i) Can we reduce the oxide of metal ‘M’ using carbon as a reducing agent? Justify.
(ii) Identify metal ‘M’. Write balanced chemical equations for its reaction with oxygen and its extraction at the cathode.
OR
B. Iron objects exposed to humid atmospheric conditions for extended periods develop a flaky, reddish-brown coating on their surfaces.
(i) What is the chemical composition of this reddish-brown substance, and what specific environmental factors trigger its formation?
(ii) Suggest two proactive industrial metallurgy methods to effectively prevent this phenomenon on structural components.
(iii) Why is zinc coating preferred over tin coating for safeguarding iron structures even if the outer layer gets scratched?
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| 27 | Sunita carried out the electrolysis of an aqueous solution of sodium chloride (brine) using a standard industrial laboratory apparatus. She observed different chemical gases bubbling out at the anode and cathode chambers respectively… | 3 |
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Fig.1 Fig. 2 Answer the following questions based on the information given above: A. Which characteristic gas was she expecting to collect at the anode terminal point and which gas at the cathode during the initial brine electrolysis setup?
B. Explain with proper scientific reasoning why the indicator bulb failed to glow when Sunita passed electrical power through pure absolute alcohol.
C. What role did the addition of dilute hydrochloric acid play in modifying the properties of the liquid medium to achieve the expected circuit response?
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For visually impaired students
Identify the specific type of chemical reaction represented by each of the following equations:
A. CuO + H2 → Cu + H2O
B. 2 KNO3 ——→ 2 KNO2 + O2 (under heat parameters) C. 4 Na + O2 → 2 Na2O |
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| 28 | Meena took 3 mL of dilute potassium hydroxide (KOH) solution in a clean test tube and added two drops of phenolphthalein solution to it, causing the solution to turn a bright pink color. She then titrated this mixture by adding dilute hydrochloric acid (HCl) drop by drop with constant swirling until the pink coloration completely vanished. Exactly 30 drops of dilute HCl were consumed to achieve this neutral state… | 4 |
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color from pink to colorless. When Meena added a drop of KOH to the solution, the color changed back to pink again. Meena now tried the activity with different volumes of KOH and recorded her observation in the table given below:
A. If Meena used concentrated HCl in place of dilute HCl, how many drops will be required for the change in color to be observed?
(a) 30 (b) < 30 (c) > 30 Justify your answer.
B. Meena measured 25 drops of dil. HCl and found its volume to be 1 mL. If Meena observed a change in color of KOH solution by using 2 mL of HCl, how many mL of KOH did she add to the test tube initially?
OR
Meena takes 15 drops of dilute HCl in the test tube and adds two drops of phenolphthalein solution to it. Then she adds KOH dropwise. Meena observes a change in color after adding 25 drops of KOH. What change in color would she observe and why?
C. Write a balanced chemical equation for the reaction taking place in the above experiment. Which of the following is true and why? The reaction is a
(a) neutralization and double displacement reaction
(b) neutralization and precipitation reaction (c) precipitation and double displacement reaction (d) neutralization, double displacement as well as precipitation reaction. |
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| 29 |
Attempt either option A or B.
A. A hydrocarbon with the formula CxHy undergoes complete combustion as shown in the following balanced chemical equation:
CxHy + 5 O2 → 3 CO2 + 4 H2O
(a) What are the values of ‘x’ and ‘y’?
(b) Give the chemical (IUPAC) name of the hydrocarbon. (c) Draw its electron dot structure. (d) Name the saturated hydrocarbon having the same number of carbon atoms as CxHy. |
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(e) Write a balanced chemical equation for the reaction of CxHy with chlorine gas in the presence of sunlight.
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B. The electronic structures of atoms P and Q are shown below:
(a) If P and Q combine to form a compound, what type of chemical bond is established between them?
(b) Give the formula of the chemical compound formed.
(c) The compound so formed is dissolved in water. Is the resultant solution acidic, basic or neutral in nature? Justify your answer.
(d) Write the chemical equation for the reaction between ‘P’ and dilute hydrochloric acid.
(e) What will be the formula of the compound formed when ‘Q’ undergoes bonding with hydrogen?
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For visually impaired students
A. A hydrocarbon with the formula CxHy undergoes complete combustion as shown in the following balanced chemical equation:
CxHy + 5 O2 → 3 CO2 + 4 H2O
(a) What are the values of ‘x’ and ‘y’?
(b) Give the chemical (IUPAC) name of the hydrocarbon.
(c) Is CxHy a saturated or an unsaturated hydrocarbon?
(d) Name the saturated hydrocarbon having the same number of carbon atoms as CxHy.
(e) Write a balanced chemical equation for the reaction of CxHy with chlorine gas in the presence of sunlight.
OR
B. Chlorine can combine with both metals and non-metals. It combines with Magnesium to form MgCl2 and with Hydrogen to form HCl.(a) What type of bond is formed between hydrogen and chlorine?
(b) Identify the type of bond formed between magnesium and chlorine.
(c) Which of the above compounds will be a good conductor of electricity in molten state and why?
(d) Comment on the physical state (solid, liquid or gas) of MgCl2 and HCl at room temperature.
(e) What is the valency of magnesium in MgCl2?
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| Section – C | Marks | |
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| 30 |
Ananya was preparing notes and she compiled the following statements from her conceptual understanding of refraction through spherical lenses: I. Convex lenses can form both real and virtual images depending upon the position of the object relative to the focus. II. Concave lenses always produce real, inverted, and magnified images regardless of the object’s position. III. For both convex and concave lenses, the relationship between focal length, image location, and object distance can be quantified using the lens formula 1f =
1v −
1u where f is the focal length, v is the image distance, and u is the object distance.Choose from the following the correct option that lists the correct statements about refraction through curved lens surfaces. |
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| 31 | Choose the correct option from the options below which explains the fundamental physical reason for us to perceive the sunset and sunrise sky as reddish in color: | 1 |
| The following question consists of two statements – Assertion (A) and Reason (R). Answer these questions by selecting the appropriate option given below: | ||
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Assertion (A): A real point object is placed at a distance of 15 cm from a concave lens of focal length 15 cm. The image will form exactly at the focus point of the lens. Reason (R): According to the lens formula 1f =
1v −
1u , substituting u = −15 cm and f = −15 cm gives the image position v at infinity.
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A. Identify the optical instrument (shown schematically as a rectangle) in the image.
B. What type of image is formed in this case?
C. Based on the measurements given in the image, calculate the focal length of the instrument.
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For visually impaired students
A. Under what conditions can a concave mirror form a virtual, erect, and magnified image?
B. Why does a convex lens act as a burning glass when solar radiation passes through it onto a piece of paper?
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B.
Calculate the following parameters based on this arrangement: (i) The net equivalent resistance of the two 3-ohm resistors aligned in this series combination.
(ii) The corresponding potential difference drop recorded across the system by the parallel-connected voltmeter.
For visually impaired students
A. State the primary difference between a series connection and a parallel connection regarding current distribution.
B. Why is an ammeter always linked in series while a voltmeter is linked in parallel inside standard electrical networks?
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B.
(i) Current flowing through the 4 ohm resistor.
(ii) Difference in the readings of ammeter A1 and A2 if any.
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For visually impaired students
A. You are given three resistors each having resistance of R ohm. Find the maximum and minimum net resistance that can be made with these three resistors.
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B. A cylindrical metal wire has a length L = 3 m, a cross-sectional area A = 0.2 mm2, and electrical resistivity ρ = 2.8 × 10−8 Ω·m. Calculate the electrical resistance of another wire fabricated from the exact same material whose length is three times the length of this wire but maintains the same cross-sectional area profile.
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(i) Identify the defect of vision and state what kind of lens is used to correct this deficiency.
(ii) Draw and label a ray diagram that shows the defect of vision in the above case before correction.
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For visually impaired students
(i) What is scattering of light? Explain with a natural example.
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(ii) Explain the physical conditions under which light scattering depends on particle size.
(iii) Give one physiological reason that causes astigmatism in the human eye.
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| 36 |
A student needs to fabricate a 0.24 Ω resistor. She has a spool of nichrome wire with a uniform diameter of 0.40 mm. The electrical resistivity of this nichrome material is 1.1 × 10−6 Ω·m. (i) Determine the cross-sectional area of the wire.
(ii) Calculate the total length of wire required to create the 0.24 Ω resistor.
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| 37 |
Magnetic field lines surrounding a magnetic material are shown schematically in the given diagram. A student states that the net strength of the magnetic field at region Y is weaker than at region X. (i) Explain with proper physical reasoning whether the student’s claim is mathematically correct.
(ii) Redraw the diagram in your answer sheet and mark the correct directional arrows of the magnetic field lines.
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| 38 |
A. What specific type of spherical lens is structurally incorporated inside the projection assembly of the slide projector to create an enlarged display?
B. Describe the characteristic nature and physical orientation profile of the real image formed directly onto the distant viewing screen.
Attempt either subpart C or D.
C. An instructor operates a slide projector equipped with an internal projection lens having a focal length f = 40 mm to project a test slide onto a screen located exactly 2040 mm behind the lens center. Calculate the exact object distance required (i.e., the separation spacing between the transparency slide and the optical lens).
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D. If a slide containing a small micro-pattern of absolute height 5 mm is placed at a distance of 41 mm in front of the projector lens (focal length f = 40 mm), determine the magnification factor and find the net vertical height of the corresponding image mapped onto the screen.
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D. An instructor operates a slide projector to view a transparency slide. The slide is positioned 50 mm away from the projection lens. The absolute vertical height of the miniature graphic on the slide is 10 mm, and the corresponding magnified image height formed onto the auditorium screen is measured to be 400 mm. Calculate the focal length of the projection lens.
For visually impaired students
Ananya worked as an apprentice in an optical instrumentation firm where high-power magnifying glasses and solar concentrators are designed and assembled. She studied the geometric layouts of light-boxes, ray-collimators, and the curvature parameters of lens modules used for concentrating solar thermal energy. Based on your understanding of spherical lenses, answer the following questions:
A. What structural kind of spherical lenses are implemented inside magnifying glasses and solar thermal light concentrators?
B. Give valid physical and optical reasons for your choices in part A.
Attempt either subpart C or D.
C. A small object is placed at a distance of 30 cm in front of a lens normally utilized as a high-power solar concentrator. The real image generated by this lens configuration is exactly three times the size of the object. Calculate the focal length of the lens.
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D. An object is placed 15 cm in front of a specialized divergent lens module, and its virtual image is successfully formed at a distance of 10 cm away from the lens center on the exact same side as the object. Calculate the focal length of this lens.
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| 39 |
Attempt either option A or B. A. The net power dissipation in the 50 Ω series resistor is monitored to be exactly 200 W. Calculate the following values based on this electrical network configuration: (i) the constant uniform current flowing through the circuit loop.
(ii) the corresponding potential difference reading registered by the voltmeter V2.
(iii) the net total terminal voltage reading registered across the battery by the voltmeter V1.
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OR B. The circuit block is connected across a steady 220 V supply main line. (i) Calculate the unique electrical resistance of one single heating element under nominal conditions.
(ii) Calculate the constant current flowing through each individual resistor when only switches S1 and S3 are kept closed.
(iii) Calculate the net power dissipated across element A when all three switches S1, S2, and S3 are closed simultaneously.
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For visually impaired students
A.
(i) Explain with scientific reasoning why safety fuses are fundamentally connected in series with all appliance networks, whereas general domestic loads are linked in parallel.
(ii) Inside a standard household circuit grid, a water geyser rated at 2200 W and an air cooler rated at 1100 W are coupled in parallel across a 220 V supply line. A protection fuse rated at 16 A is installed in the line.
(a) Calculate the total combined current drawn by both the geyser and the air cooler.
(b) Determine whether the 16 A safety fuse rating is appropriately dimensioned for this network profile or if it will blow up.
OR
B. Two heavy electrical loads with resistances R1 = 8 Ω and R2 = 24 Ω are wired in a parallel configuration across a 24 V DC power source line. The network stays continuously active for exactly 10 minutes.(i) Calculate the total thermal heat energy generated inside both resistors during this span.
(ii) If each resistor has a safe physical power rating limit of 80 W, determine whether it is structurally safe to run these resistors inside the circuit network.
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