Q: Q10. A carbon compound with formula C ₃ H ₈ belongs to:

Option C: Alkane. Alkanes follow the general formula CH ₂₊₂ . C ₃ H ₈ is propane.

Question 1

Q1. Which of the following reactions is used in thermite welding?

Accepted Answer

Option D: Redox reaction. In thermite reaction, aluminium reduces iron oxide to iron while itself gets oxidised. Oxidation and reduction occur simultaneously.

Question 2

Q2. The SI unit of electric power is:

Accepted Answer

Option C: Watt. Electric power is the rate at which electrical energy is consumed and is measured in watts.

Question 3

Q3. Which structure in amoeba helps in capturing food?

Accepted Answer

Option C: Pseudopodia. Amoeba extends pseudopodia around food particles for engulfing and ingestion.

Question 4

Q4. Which of the following metals reacts vigorously with cold water?

Accepted Answer

Option B: Sodium. Sodium is highly reactive and reacts violently with cold water to form sodium hydroxide and hydrogen gas.

Question 5

Q5. Which process is responsible for movement of water from roots to leaves in plants?

Accepted Answer

Option C: Transpiration pull. Loss of water through stomata creates suction force that pulls water upward through xylem.

Question 6

Q6. A student observed that iron nails kept in copper sulphate solution develop a reddish-brown coating. The coating is of:

Accepted Answer

Option B: Copper. Iron displaces copper from copper sulphate solution because iron is more reactive than copper.

Question 7

Q7. A bulb connected to a 220 V supply draws 0.5 A current. The power consumed is:

Accepted Answer

Option A: 110 W. Using P = VI = 220 × 0.5 = 110 W

Question 8

Q8. A student touches the leaves of a touch-me-not plant and notices folding of leaves. This movement is due to:

Accepted Answer

Option C: Nastic movement. Touch-me-not plants show nastic movement, which is independent of direction of stimulus.

Question 9

Q9. Which of the following statements about magnetic field lines is correct?

Accepted Answer

Option C: They form closed continuous curves. Magnetic field lines emerge from north pole and enter south pole outside the magnet, forming closed loops.

Question 10

Q10. A carbon compound with formula C ₃ H ₈ belongs to:

Accepted Answer

Option C: Alkane. Alkanes follow the general formula C H ₂ ₊₂ . C ₃ H ₈ is propane.

Question 11

Q11. Doctors advise using ORS solution during dehydration because it helps:

Accepted Answer

Option B: Restore water and salt balance. ORS replenishes essential salts and fluids lost during dehydration.

Question 12

Q12. Assertion (A): Graphite conducts electricity. Reason (R): Graphite contains free electrons.

Accepted Answer

Option A: Both A and R are true and R is correct explanation of A. Each carbon atom in graphite contributes one free electron, allowing conduction.

Question 13

Q13. Assertion (A): Concave lenses always form diminished images. Reason (R): Concave lenses diverge light rays.

Accepted Answer

Option A: Both A and R are true and R is correct explanation of A. Concave lenses spread light rays outward, producing virtual, erect, and diminished images.

Question 14

Q14. Case Study: A student connected a battery, key, resistor, and ammeter in series. When the key was closed, the ammeter showed 0.2 A current. On adding another resistor in series, the current decreased. Why did current decrease?

Accepted Answer

Option B: Total resistance increased. According to Ohm's law, increasing resistance decreases current if voltage remains constant.

Question 15

Q15. Case Study: A farmer noticed excessive algae growth in a nearby pond due to fertilizer runoff from fields. This phenomenon is called:

Accepted Answer

Option B: Eutrophication. Excess nutrients promote rapid algae growth, reducing oxygen levels in water bodies.

Question 16

Q16. A student states that all exothermic reactions are combustion reactions. Which option disproves this statement?

Accepted Answer

Option B: Respiration. Respiration releases energy slowly without flame, so it is exothermic but not combustion. (Conceptual trap)

Question 17

Q17. Which statement correctly explains why acids do not show acidic behaviour in absence of water?

Accepted Answer

Option C: H ⁺ ions are not released without water. Acids show acidic properties only when they ionise in aqueous solution to produce H ⁺ ions.

Question 18

Q18. A ray of light enters from air into water obliquely. Which quantity remains unchanged?

Accepted Answer

Option D: Frequency. During refraction, frequency remains constant while speed and wavelength change. (High-frequency tricky concept)

Question 19

Q19. Which of the following organisms is most likely to accumulate maximum harmful chemicals through biomagnification?

Accepted Answer

Option D: Hawk. Top consumers accumulate highest concentration of toxic substances through food chains.

Question 20

Q20. A student observes that image formed by a concave mirror is real, inverted, and highly diminished. The object is placed:

Accepted Answer

Option C: Beyond centre of curvature. When the object is far beyond centre of curvature, the image forms between F and C and becomes diminished.

Mock Test 05 Performance Solutions

Detailed Question Analysis

Q1. Which of the following reactions is used in thermite welding?

Q2. The SI unit of electric power is:

Q3. Which structure in amoeba helps in capturing food?

Q4. Which of the following metals reacts vigorously with cold water?

Q5. Which process is responsible for movement of water from roots to leaves in plants?

Q6. A student observed that iron nails kept in copper sulphate solution develop a reddish-brown coating. The coating is of:

Q7. A bulb connected to a \(220\,\mathrm{V}\) supply draws \(0.5\,\mathrm{A}\) current. The power consumed is:

Q8. A student touches the leaves of a touch-me-not plant and notices folding of leaves. This movement is due to:

Q9. Which of the following statements about magnetic field lines is correct?

Q10. A carbon compound with formula \(\mathrm{C_3H_8}\) belongs to:

Q11. Doctors advise using ORS solution during dehydration because it helps:

Q12. Assertion (A): Graphite conducts electricity. Reason (R): Graphite contains free electrons.

Q13. Assertion (A): Concave lenses always form diminished images. Reason (R): Concave lenses diverge light rays.

Q14. Case Study: A student connected a battery, key, resistor, and ammeter in series. When the key was closed, the ammeter showed \(0.2\,\mathrm{A}\) current. On adding another resistor in series, the current decreased. Why did current decrease?

Q15. Case Study: A farmer noticed excessive algae growth in a nearby pond due to fertilizer runoff from fields. This phenomenon is called:

Q16. A student states that all exothermic reactions are combustion reactions. Which option disproves this statement?

Q17. Which statement correctly explains why acids do not show acidic behaviour in absence of water?

Q18. A ray of light enters from air into water obliquely. Which quantity remains unchanged?

Q19. Which of the following organisms is most likely to accumulate maximum harmful chemicals through biomagnification?

Q20. A student observes that image formed by a concave mirror is real, inverted, and highly diminished. The object is placed:

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Mock Test 05 Performance Solutions

Detailed Question Analysis

Q1. Which of the following reactions is used in thermite welding?

Q2. The SI unit of electric power is:

Q3. Which structure in amoeba helps in capturing food?

Q4. Which of the following metals reacts vigorously with cold water?

Q5. Which process is responsible for movement of water from roots to leaves in plants?

Q6. A student observed that iron nails kept in copper sulphate solution develop a reddish-brown coating. The coating is of:

Q7. A bulb connected to a \(220\,\mathrm{V}\) supply draws \(0.5\,\mathrm{A}\) current. The power consumed is:

Q8. A student touches the leaves of a touch-me-not plant and notices folding of leaves. This movement is due to:

Q9. Which of the following statements about magnetic field lines is correct?

Q10. A carbon compound with formula \(\mathrm{C_3H_8}\) belongs to:

Q11. Doctors advise using ORS solution during dehydration because it helps:

Q12. Assertion (A): Graphite conducts electricity. Reason (R): Graphite contains free electrons.

Q13. Assertion (A): Concave lenses always form diminished images. Reason (R): Concave lenses diverge light rays.

Q14. Case Study: A student connected a battery, key, resistor, and ammeter in series. When the key was closed, the ammeter showed \(0.2\,\mathrm{A}\) current. On adding another resistor in series, the current decreased. Why did current decrease?

Q15. Case Study: A farmer noticed excessive algae growth in a nearby pond due to fertilizer runoff from fields. This phenomenon is called:

Q16. A student states that all exothermic reactions are combustion reactions. Which option disproves this statement?

Q17. Which statement correctly explains why acids do not show acidic behaviour in absence of water?

Q18. A ray of light enters from air into water obliquely. Which quantity remains unchanged?

Q19. Which of the following organisms is most likely to accumulate maximum harmful chemicals through biomagnification?

Q20. A student observes that image formed by a concave mirror is real, inverted, and highly diminished. The object is placed:

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