Physical Science Important Questions
High-frequency questions from BSE AP Class 10 Physical Science public exams — Chemistry (Ch.1–4) and Physics (Ch.9–12), matching the General Science Paper I pattern.
Ch. 1 Chemical Reactions and Equations
- 1Write a balanced chemical equation for the reaction of iron with steam. What type of reaction is this?
- 2What happens when zinc granules are added to dilute sulphuric acid? Write the balanced equation. What will you observe?
- 3Identify the type of reaction: 2Mg + O₂ → 2MgO. Explain why magnesium undergoes this reaction easily.
- 4Explain the difference between exothermic and endothermic reactions with one example each.
- 5Why do we apply paint or grease to iron articles? Explain in terms of the chemical reaction involved.
- 6What is the difference between displacement and double displacement reactions? Give one example of each.
Ch. 2 Acids, Bases and Salts
- 1What happens when excess CO₂ is passed through limewater that has already turned milky? Write the equation.
- 2A student adds a few drops of universal indicator to three solutions X, Y, Z and records pH values of 3, 7, and 10 respectively. Identify the nature of each solution.
- 3How is NaOH prepared commercially? Write the equation for the electrolysis of brine. What are the by-products?
- 4Explain the process of neutralisation. Why is baking soda used to treat ant bite (which injects methanoic acid)?
- 5What is the difference between washing soda and baking soda? Give their chemical formulae and one use of each.
- 6Why does dry HCl gas not turn blue litmus red, but HCl dissolved in water does? What does this tell us about acids?
Ch. 3 Metals and Non-metals
- 1Name the metals that react with cold water, hot water, and steam. Write one equation for each.
- 2What is the reactivity series? Using the reactivity series, explain why copper does not displace zinc from zinc sulphate solution.
- 3Explain the formation of NaCl with a diagram showing transfer of electrons. Why does NaCl have a high melting point?
- 4What is thermite reaction? Write the balanced equation. State one important practical application.
- 5Describe the process of extraction of aluminium from bauxite ore. Why is electrolysis used and not reduction by carbon?
- 6What is corrosion? How is it different from rusting? State two methods to prevent rusting of iron.
Ch. 4 Carbon and its Compounds
- 1What is the special property of carbon that allows it to form a large number of compounds? Explain catenation and tetravalency.
- 2Give the structural formula of ethanol and ethanoic acid. How can you distinguish between the two using a simple test?
- 3What happens when ethanol is oxidised using acidic KMnO₄? Write the equation and name the product.
- 4Explain the reaction between ethanol and ethanoic acid. What is the product called? What is the catalyst used?
- 5What are soaps? How are they made from fats/oils? Why do soaps not work well in hard water?
- 6Explain why ethene undergoes addition reaction while ethane undergoes substitution reaction. Give one equation for each.
Ch. 9 Light — Reflection and Refraction
- 1A concave mirror has focal length 15 cm. An object is placed 40 cm from the mirror. Find the image distance and magnification using the mirror formula.
- 2Draw a ray diagram to show the image formed when an object is placed between the pole and focus of a concave mirror.
- 3State Snell's law of refraction. The refractive index of glass is 1.5. If light enters glass from air at an angle of 30°, find the angle of refraction.
- 4A convex lens of focal length 20 cm forms a real, inverted, magnified image when an object is placed at 30 cm. Find the image position and nature.
- 5Define power of a lens. A doctor prescribes a lens of power −2.5 D. What type of lens is it? What is its focal length?
- 6Why does a ray of light bend when it passes obliquely from one medium to another? What happens when light falls normally on a glass surface?
Ch. 10 The Human Eye and the Colourful World
- 1A person cannot see objects beyond 4 m. Name the defect. What type and power of corrective lens is needed?
- 2Draw a ray diagram to show how a convex lens corrects hypermetropia. State the near point of a hypermetropic person.
- 3What is the Tyndall effect? Give two natural examples. Why does the sky appear blue?
- 4Explain the dispersion of white light through a glass prism. Why does the sky appear red at sunrise and sunset?
- 5Distinguish between myopia and hypermetropia. State one cause and the corrective lens for each defect.
Ch. 11 Electricity
- 1Three resistors of 5 Ω, 10 Ω, and 15 Ω are connected in parallel across a 30 V battery. Find the current through each and the total current.
- 2An electric heater draws 4 A from a 220 V supply. Calculate the resistance of the heater and the energy consumed in 2 hours.
- 3State Ohm's law. Draw the V–I graph for an ohmic conductor and explain what its slope represents.
- 4Why is the filament of an electric bulb made of tungsten? Why is it filled with an inert gas and not air?
- 5Define electric power. Derive P = I²R = V²/R. Calculate the power of a device drawing 0.5 A at 220 V.
Ch. 12 Magnetic Effects of Electric Current
- 1State Fleming's Left-Hand Rule. In what device is this rule applied? Describe the principle of a DC motor.
- 2What is electromagnetic induction? State the factors that affect the magnitude of the induced EMF.
- 3Explain the difference between an AC generator and a DC generator. Draw a simple diagram of an AC generator.
- 4Why are power lines transmitted at high voltage and low current? How does a transformer help achieve this?
- 5A step-down transformer converts 2200 V to 220 V. If the primary coil has 1000 turns, find the number of turns in the secondary coil.
- 6What is a solenoid? Draw the magnetic field pattern around a solenoid. How does it resemble a bar magnet?