Class 7 Science: Sample Paper Solutions - 3 | Sample Papers For Class 7 PDF Download

Time: 3 Hours  
Total Marks: 80

General Instructions

This question paper consists of 34 questions in total and all questions are compulsory.

• Questions 1–7 are multiple-choice questions and carry 1 mark each. Write the correct answer.
• Questions 8–17 are very short answer questions and carry 2 marks each.
• Questions 18–28 are short answer questions and carry 3 marks each.
• Questions 29–34 are long answer questions and carry 5 marks each.

Section – A

Q1. Which is a natural indicator?   (1 marks)
(a) Phenolphthalein 
(b) Methyl orange 
(c) Turmeric 
(d) Litmus

Ans: (c) 
Turmeric turns red in bases, it’s plant-based.

Q2. What is the magnetic effect of electric current?   (1 marks)
(a) Heating 
(b) Lighting 
(c) Magnetism 
(d) Chemical

Ans: (c)
Current produces a magnetic field, as in electromagnets.

Q3. Which non-metal is liquid at room temperature?   (1 marks)
(a) Bromine 
(b) Iodine 
(c) Sulphur 
(d) Phosphorus

Ans: (a) 
Bromine – Only liquid non-metal at room temperature.

Q4. What is a combination reaction?   (1 marks)
(a) Decomposition 
(b) Two substances form one 
(c) Displacement 
(d) Double displacement

Ans: (b) 
Two substances form one – e.g., H₂ + O₂ → H₂O.

Q5. Which gland produces insulin?   (1 marks)
(a) Thyroid 
(b) Adrenal 
(c) Pancreas 
(d) Pituitary

Ans: (c) 
Pancreas – Regulates blood sugar; deficiency causes diabetes.

Q6. What is land breeze?   (1 marks)
(a) From land to sea 
(b) From sea to land 
(c) High pressure 
(d) Low pressure

Ans: (a) 
From land to sea – At night, cool air from land flows to sea.

Q7. What is oscillatory motion?   (1 marks)
(a) Circular 
(b) To and fro 
(c) Straight 
(d) Random

Ans: (b) 
To and fro – e.g., pendulum swing.

Section – B

Q8. What is an acid-base indicator?   (2 marks)

Ans: A substance that changes colour in acids and bases, e.g., litmus turns red in acids and blue in bases.

Q9. What is a closed circuit?   (2 marks)

Ans: A complete path allowing current to flow with no breaks, enabling devices to work.

Q10. Name two reactive metals.   (2 marks)

Ans: Sodium and Potassium – both react vigorously with water and are stored in kerosene.

Q11. What is decomposition reaction?   (2 marks)

Ans: Breakdown of a compound into simpler substances, e.g., electrolysis of water → H₂ + O₂.

Q12. What is menstrual cycle?   (2 marks)

Ans: Monthly cycle in females involving ovulation and shedding of uterine lining if fertilisation does not occur.

Q13. What is insulation in heat transfer?   (2 marks)

Ans: Using poor conductors (e.g., wool, plastic) to prevent heat transfer.

Q14. What is non-uniform motion?   (2 marks)

Ans: Motion where speed changes; unequal distances covered in equal times, e.g., accelerating car.

Q15. What is haemoglobin?   (2 marks)

Ans: Iron-rich protein in red blood cells that carries oxygen from lungs to tissues.

Q16. What is parasitic nutrition?   (2 marks)

Ans: Mode of nutrition where an organism lives on/in a host and derives nutrients, e.g., cuscuta on plants.

Q17. What is a concave mirror?   (2 marks)

Ans: A mirror curved inward; forms real or virtual images; used in torches for focused light.

Section – C

Q18. How do bases feel and taste? Give examples.   (3 marks)

Ans: Bases feel soapy/slippery and taste bitter. Examples: Soap (slippery), Baking soda (bitter).

Q19. Explain Ohm’s law.   (3 marks)

Ans: At constant temperature, current (I) ∝ voltage (V) and inversely ∝ resistance (R).
Formula: I = V/R.

Q20. How do non-metals react with acids?   (3 marks)

Ans: Non-metals usually do not react with acids. Exceptions: sulphur reacts with concentrated acids forming oxides.

Q21. Explain double displacement reaction with example.   (3 marks)

Ans: Exchange of ions between two compounds. Example:
AgNO₃ + NaCl → AgCl ↓ + NaNO₃ (precipitation reaction).

Q22. What are secondary sexual characteristics?   (3 marks)

Ans: Features that develop at puberty, not directly linked to reproduction, e.g., beard in boys, breast development in girls.

Q23. How does convection occur in air?   (3 marks)

Ans: Hot air rises (less dense), cool air sinks (denser), forming convection currents, e.g., room heater circulation.

Q24. What is the time period of a pendulum?   (3 marks)

Ans: Time for one complete oscillation. Depends on length of string, not mass of bob.

Q25. Explain kidney function in excretion.   (3 marks)

Ans: Kidneys filter blood to remove urea, excess water and salts, forming urine; maintain fluid and ionic balance.

Q26. How do roots help in soil conservation?   (3 marks)

Ans: Roots bind soil particles, prevent erosion by water/wind, and reduce runoff.

Q27. What is lateral inversion?   (3 marks)

Ans: Left–right reversal in a plane mirror. Example: “b” looks like “d”.

Q28. What is lunar eclipse?   (3 marks)

Ans: Occurs when Earth comes between Sun and Moon; Earth’s shadow falls on Moon (total or partial).

Section – D

Q29. (a) What is hypothesis?    (5 marks)
(b) Explain scientific method steps. 
(c) Give an example.

Ans: (a) Hypothesis → A testable explanation for an observation.
(b) Steps → Observation → Hypothesis → Experiment → Analysis → Conclusion.
(c) Example → Testing whether plants need sunlight for growth.

Q30. (a) What are strong and weak acids?     (5 marks)
(b) Give examples. 
(c) Explain uses.

Ans: (a) Strong acids ionise completely (e.g., HCl). Weak acids ionise partially (e.g., acetic acid).
(b) Strong: HCl, H₂SO₄; Weak: CH₃COOH, H₂CO₃.
(c) Uses: In batteries (sulphuric acid), cleaning (HCl), food preservation (acetic acid).

Q31. (a) What is an electric bell?     (5 marks)
(b) Explain working. 
(c) Draw diagram.

Ans: (a) An electric bell works on electromagnetism.
(b) Current energises electromagnet → pulls hammer → strikes gong → contact breaks → cycle repeats.
(c) Diagram includes: battery, switch, electromagnet, hammer, gong, contact screw.

Q32. (a) What is corrosion?     (5 marks)
(b) Explain prevention. 
(c) Give examples.

Ans: (a) Gradual deterioration of metals by reaction with air/moisture.
(b) Prevention: Painting, galvanisation, alloying, cathodic protection.
(c) Examples: Rusting of iron, tarnishing of silver, green coating on copper.

Q33. (a) What is voice change in adolescence?     (5 marks)
(b) Explain for boys and girls. 
(c) Role of hormones.

Ans: (a) Deepening/cracking of voice due to growth of voice box (larynx).
(b) Boys → Larger larynx, Adam’s apple, deeper voice.
Girls → Slight deepening, smoother voice.
(c) Hormones: Testosterone (boys), Estrogen (girls).

Q34. (a) What is temperature?     (5 marks)
(b) Explain scales. 
(c) How is heat different?

Ans: (a) Temperature → Degree of hotness or coldness.
(b) Scales: Celsius (°C), Fahrenheit (°F), Kelvin (K).
(c) Heat → Total energy transferred; Temperature → Measure of average kinetic energy of particles.