Physical Science Important Questions

An object is placed 15 cm in front of a concave mirror of focal length 10 cm. Use the mirror formula to find the image distance. State whether the image is real or virtual.

What is magnification? A concave mirror produces an image three times the size of the object. If the object is 20 cm from the mirror, find the image distance. Is the image erect or inverted?

Distinguish between a concave mirror and a convex mirror — types of images formed and one practical use of each.

State Snell's law of refraction. A ray of light passes from air (n=1) into glass (n=1.5). If angle of incidence is 30°, find the angle of refraction.

An object is placed 30 cm from a convex lens of focal length 10 cm. Using the lens formula, find image distance and state the nature of the image.

Define power of a lens. A convex lens has focal length 25 cm. Calculate its power. Two such lenses are placed in contact — what is the combined power?

Describe myopia. Explain its cause and how it is corrected. Draw a ray diagram showing the defect and its correction.

What is the power of accommodation of the human eye? How does it change with age? What condition does this lead to in old age?

Three resistors of 4 Ω, 6 Ω, and 12 Ω are connected in parallel across a 12 V battery. Find equivalent resistance, total current from battery, and current through each resistor.

State Joule's law of heating. A 60 W bulb is used 5 hours daily. Calculate electrical energy consumed in one week (in kWh). What is the cost at ₹4 per unit?

Define electric power. Derive P = I²R from Ohm's law. A heating element of 5 Ω draws 4 A. Find power and heat produced in 10 minutes.

State Fleming's left-hand rule. Explain how it gives the direction of force on a current-carrying conductor in a magnetic field.

Explain the principle of electromagnetic induction. State Fleming's right-hand rule and name one device that works on this principle.

Compare AC and DC — direction of flow, generation method, transmission efficiency, domestic use.

Balance: (a) Fe + O₂ → Fe₂O₃ (b) Al + HCl → AlCl₃ + H₂ (c) Ca(OH)₂ + HCl → CaCl₂ + H₂O

Classify the following reactions and give one example of each: combination, decomposition, single displacement, double displacement, oxidation-reduction.

What is oxidation and reduction? In CuO + H₂ → Cu + H₂O, identify the substance oxidised and the substance reduced. Name the reducing agent.

Explain the pH scale. A solution has pH 3 — is it acidic, basic, or neutral? How does pH change when water is added to an acid?

Name three acid-base indicators and describe the colour change each shows in acidic and basic solutions.

Describe the preparation and uses of: (a) baking soda (NaHCO₃) (b) washing soda (Na₂CO₃·10H₂O) (c) bleaching powder (CaOCl₂).

Write the electronic configuration of (a) Sodium (Z=11) (b) Chlorine (Z=17) (c) Calcium (Z=20). State the valency of each.

Define isotopes and isobars. Give one example of each. Why do isotopes of the same element have identical chemical properties?

Describe how atomic radius changes across a period (left to right) and down a group. Give reasons for both trends.

State the modern periodic law. How does it differ from Mendeleev's periodic law? State two advantages of the modern periodic table.

Arrange Cu, Zn, Fe, Al in order of reactivity (most to least reactive). Explain how you determined the order using the reactivity series.

Describe electrolytic refining of copper. Why is this method used for purification? What happens at the anode and cathode?

Define corrosion. Why does iron rust but aluminium not corrode easily? Write the equation for rusting of iron. Name two methods to prevent corrosion.

Name the functional groups in: (a) ethanol (b) ethanoic acid (c) methanal. Write the structural formula for each.

What is a homologous series? Give the first three members of the alkane series. State two characteristics of a homologous series.

Explain how soap acts as a cleaning agent. Define: micelle, hydrophilic, hydrophobic. Why does soap not work well in hard water?