The Dr. Homi Bhabha Balvaidnyanik Competition (DHBBVC) is one of Maharashtra’s most prestigious science competitions for school students. It is organized by the Mumbai Science Teachers’ Association.
(MSTA) to encourage scientific thinking, curiosity, experimentation, and problem-solving skills. The competition has been conducted since 1981.
Question Paper 2025
Which of the followings are fundamentals units?
P) kilometer Q) kilogram R) cusec S) kelvin
A. Q, S
B. P, S
C. P, Q
D. Q, R
View Answer
A
2.A car is moving with the deacceleration 6 m/s². What is the initial velocity of the car which stops after 2 second?
A. 2m/s
B. 3m/s
C. 6m/s
D. 12m/s
View Answer
A
3. Which of the following factors of the circuit affect the power consumed in it?
P) Applied potential difference Q) Resistance
R) Temperature of the conductor S) Current flowing
A. P, Q
B. P, Q, R, S
C. P, Q, S
D. Q, R, S
View Answer
B
4. At what position an object be placed in front of a concave mirror so that, its image is of the same size?
A. At F
B. Between F and 2F
C. At 2F
D. Beyond 2F
View Answer
C
5.Which of the following are web browsers?
P) Google Q) Google Chrome R) Mozilla Firefox S) Microsoft Edge
A. P, Q, R
B. P, Q, S
C. Q, R, S
D. P, Q, R, S
View Answer
C
6. A simple pendulum is taken from the Earth to the Moon. What will be the effect on time period?
A. Decreases, due to absence of atmosphere
B. Increases, due to lower gravity
C. Independent on gravity, remains the same
D. Decreases, because the moon is smaller
View Answer
B
7. Light is incident on surface S1, S2, S3 as shown in figures.
On which surfaces the angles of incidence is equal to the angle of reflection.
A. S1 and S2
B. S1 and S3
C. S2 and S3
D. S1, S2 and S3
View Answer
D
8. A force F produces an acceleration of 8 m/s² in an object of mass m¹ and 24 m/s² in an object of mass m². What acceleration would be produced if both the masses were tied together and applied same force on it?
A. 3m/s²
B. 6m/s²
C. 12m/s²
D. 16m/s²
View Answer
B
9. Following devices are connected in different circuits. In which of those shows an equivalent current?
A. P, R
B. P, S
C. P, Q
D. Q, S
View Answer
B
10. If the frequency of a sound wave is doubled while keeping speed constant, what is its new wavelength?
A. A λ
B. 2λ
C. λ/2
D. λ/4
View Answer
C
11. Which of the following are Input devices used for computer?
P) Keyboard Q) Mouse R) Monitor S) Joystick T) Printer
A. P, Q, R
B. P, Q, S
C. P, Q, T
D. P, Q, R, T
View Answer
B
12.Match the following:
A. . i-p-x ii-q-y iii- r-z
B. i-r-z ii-p-y iii- q-x
C. i-r-x ii-p-z iii- q-y
D. i-q-z ii-r-y iii- p-x
View Answer
B
13. Find the current flowing through the resistance 100 Ω in the given circuit.
A. 1A
B. 2A
C. 0.5A
D. 0.2A
View Answer
C
14. At which of the following temperature does water produces the greatest buoyant force?
P) 0°C Q) 4°C R) 277.15K S) 39.2°F
A. P, Q and R
B. Q, R and S
C. P, R
D. Q, R
View Answer
B
15. In velocity-time graph of uniformly accelerated motion of an object A(ABCD) shows.
A. Acceleration
B. Distance travelled
C. Speed
D. Average speed
View Answer
B
16. Three spherical mirrors are made from the same hollow glass sphere. Which of the following factor will not be common among them
A. Center of curvature
B.Radius of curvature
C. Pole
D.Focal length
View Answer
C
17. Two identical masses of an objects X and Y are placed on a table as shown in figure. What is the ratio of pressure exerted by X and Y on a table?
A. 1:1
B. 1:2
C. 2:1
D. 1:4
View Answer
B
18. Which of the following materials is used to make the core of an electromagnet?
A. Copper
B. Plastics
C. Iron
D. Rubber
View Answer
C
19. Read the following assertion (X) and Reason (Y). Choose the correct option.
Assertion (X):balloon filled with gas burst when it rises to a certain height.
Reason (y): As the balloon rises the external air pressure decreases, so the gas inside the balloon expands the size of the balloon increases.
A. Both X and Y are true and Y is the correct explanation of X.
B. Both X and Y are true and Y is not the correct explanation of X
C. X is true but Y is false
D. X is false but Y is true
View Answer
A
20.Match the following correct option for work done by the gravitational force.
A. 1 – a- i, 2- b – iii, 3 – c – ii
B. 1 – c- ii, 2- a – i, 3 – b – iii
C. 1 – b- ii, 2- c – i, 3 – a – iii
D. 1 – b- iii, 2- c – ii, 3 – a – i
View Answer
C
21. Which of the following devices is used to measure the density of liquids?
A. Measuring cylinder
B. Hygrometer
C. Calorimeter
D. Hydrometer
View Answer
D
22. Four charged objects P, Q, R and S. Object P attracts Q but repels R. Object R attracts positively charged S. Then which another object is positively chargeds?
A. Q
B. P
C. R
D. None of the above
View Answer
A
23. A bullet is moving with velocity 15m/s having its linear momentum 300g.cm/s. Find the mass of the bullet?
A. 0.2 g
B.2 g
C. 20 g
D. 200 g
View Answer
A
24. While playing the veena when we press the string with a finger, which properties of sound changes?
X) Frequency Y) Amplitude Z) Pitch
A. X, Y
B. X, Z
C. X, Z
D. X, Y, Z
View Answer
C
25. Two plane mirrors are inclined at an angle of 90° to each other and an object is placed between them. How many images of the object will be formed?
A. 3
B. 4
C. 5
D. 6
View Answer
A
26. How much KW power is required for a machinegun to fire 60 bullets per minute with the velocity of 1000 m/s, and the mass of each bullet is 25g?
A. 12.25
B. 12.50
C. 12.05
D. 12.75
View Answer
B
27. Which of the following character encoding standard is developed by C-DAC for writing different Indian language scripts?
A. ASCII
B. ISCII
C. UNOCODE
D. EBCDIC
View Answer
B
28. Two object each of mass m moving with a constant velocity v in opposite direction and collide with another. What is the velocity of the compound body after the collision?
A. v
B. v/2
C. 2v
D. zero
View Answer
D
29. Which of the following devices are working on principle of electromagnetism?
P) Electric Iron Q) Electric Fan R) Induction Motor S) MRI Machine
A. P, R, S
B. P, Q, R
C. P, Q, S
D. Q, R, S
View Answer
D
30. A sound wave passes from air medium to water medium which of the following characteristics remains an unchanged?
A. Speed
B. Frequency
C. Wavelength
D. Amplitude
View Answer
B
31. A student melts the ice cubes and take its weight then freezes the water back into ice & again weighs. The mass remains the same. But the volume is different in process If the students wanted to prove that this is a physical change. Which additional evidence would be most convincing?
A. The density of ice is less than water
B. The process is reversible without forming the new substances
C. Ice is colder than water
D. Both states are composed of H₂O molecules
View Answer
B
32. An iron bridge near the sea shows faster rusting compared to an iron gate in a dry rural area. Which combination of factors is most responsible for this
A. High oxygen + low moisture
B. High moisture + presence of salts in air
C. Low Oxygen + low moisture
D. High temperature + absence of salts
View Answer
B
33.If a detergent solution has 0.5 mol/L concentration, e ach molecule ha a molar mas of 600g/mol, the total mass of detergent in 2 L is:
A. 0.3 g
B. 300 g
C. 600 g
D. 1200g
View Answer
C
34. Assertion (E): Argon is placed outside the overlapping region of the Venn diagram it is a monoatomic element.
Reason R): Noble gases exist as single atoms and do not form molecule under normal conditions.
A. Both E and R are true, and R is the correct explanation of E
B. Both E and R are true, but R is not the correct explanation of E
C. E is true, but R is false
D. E is false, but R is true
View Answer
A
35. Arrange the following models in chronological order of their proposal:
- Thomson’s model
- Dalton’s atomic theory
- Bohr’s model
- Rutherford’s model
A. 2 → 1 → 4 → 3
B. 1 → 2 → 3→ 4
C. 4 → 3 → 2→ 1
D. 2 → 4 → 1→3
View Answer
A
36. Consider the following two reactions:
1.3Fe +4 H₂O → Fe 3O4 + X
2.Fe 3O4 + 4CO → 3Fe + Y
Identify which gas will be evolved in place of X & Y, by which method of movement of gas they are collected
A.X: carbon dioxide, Y: Hydrogen, upward & downward respectively
B. X: Hydrogen, Y: carbon dioxide, downward & upward respectively
C. X: carbon dioxide, Y: Hydrogen, both by downward method
D. X: Hydrogen, Y: Carbon dioxide, both by upward method
View Answer
B
37. P, Q, R, S, T are the solution given, identify their type.
P-Salt solution, Q-Muddy water, R-Milk, S-Fog and T- Modern medicine that can be easily absorbed by the body
A. (P-True solution, Q-Suspension, R-Colloid, S-Aerosol (Gas in liquid T- Colloid solution)
B. (P-Suspension, Q-True solution, R-Foam (Gas or solid in liquid) S-Gel, T- suspension
C. Food . P-True solution, Q-Suspension, R- Emulsion. S- Aerosol, T- Colloid solution)
D. (P-Colloid, Q-Suspension, R-True solution, S-Gel, T- Foam (Gas or solid in liquid)
View Answer
C
38. Consider the following alloy or metal and their properties. Identify the INCORRECT pair.
A. Stainless steel (good quality) – Contains Fe, Cr, Ni, highly resistant to corrosion
B. Mild steel – Ni replaced by Mn, prone to cracks
C. Galvanized iron – Protected by a thin layer of Zn
D. Pure Iron – Harder and more durable than stainless steel
View Answer
D
39. Match the following metals with the characteristic corrosion product:
A. 1-c, 2-b, 3-a
B. 1-b, 2-a, 3-c
C. 1-a, 2-c, 3-b
D. 1-c, 2-a, 3-b
View Answer
A
40. Which of the following substances obey the law of constant proportion?
- Water (H₂O) Q. Carbon dioxide CO2 R. Brass (Cu+ Zn)
S. Methane (CH4) T. Steel (Fe+ C)
A. P, Q, and S
B. P, R, and T
C. Q and R
D. P and S
View Answer
A
41. Which graph correctly represent Avogadro law, Volume vs number of molecules (N) at constant Temperature (T) & pressure (P)?
View Answer
A
42. How many water molecules (H₂O) have the same total mass as one HNHO3 molecule?
(Given: atomic mass of H=1, 0=16, N=14)
A. 1:5
B. 2:1
C. 3:5
D. 4:2
View Answer
C
43. In an experiment:
- Solution A turns phenolphthalein pink
- Solution B reacts with A to form white precipitate
What are A and B?
A. A= NaOH, B=CuSO₄
B. A= KOH, B=CaCl₂
C. A= NH₄ OH, B=AgNo₃
D. A= Ba(OH) ₂, B=H₂SO₄
View Answer
D
44. A laboratory technician prepares two solutions:
Solution X: 1M HCI
Solution Y: 1M CH₃COOH
Then which statement is true for both solutions?
A. Both have same [H⁺] because both are 1 mole
B. X has higher [H ⁺] than Y because” X” Ionizes completely & “Y” ionizes partially.
C. Y has higher [H ⁺] because “Y” is organic acid
D. Both are neutral solutions
View Answer
B
45. A metal X reacts with dilute HCI to form a aqueous solution compound XCI₂, whose pH less than 7 and H₂, gas. The same metal reacts with 0₂, to form XO, which neutralizes HNO₃ then what is X?
A. Ca
B. Mg
C. Fe
D. Cu
View Answer
C
46. A coal mine produces lignite. It is later converted to coke and used in blast furnaces. Meanwhile, methane escapes from mines, causing safety hazards. Identify P, Q, R., S.
. Lignite has (P) % carbon.
. Coke is used as a (Q) agent
. Methane is a (R) fuel with molecular mass (S).
Which option is correct?
A. (P) ~25-35, (Q) reducing, (R) clean, (S) 16
B. (P) ~80-90, (Q) oxidizing, (R) poisonous, (S) 44
C. P) ~25-35, (Q) oxidizing, (R) clean, (S) 28
D. (P) ~90-95, (Q) reducing, (R) inert, (S) 12
View Answer
A
47. Identify the correct ascending order of hardness of Graphite, Coke, Diamond.
View Answer
C
A. Diamond < Coke < Graphite
B. Graphite < Coke < Diamond
C. Coke < Graphite < Diamond
D. Coke <Diamond < Graphite
View Answer
B
48. CH₃O-CO- CH₂-CH(CH₃)- CH₂- CHO
A. 3-Methyl-5-oxohexanal
B. 3-Methyl-5-oxopentanal
C. 4-Methyl-5-oxohexanal
D. 5-Methyl-4-oxohexanal
View Answer
A
49.Which pair correctly links process and chemical principle?
A. Teflon coating-Free radical polymerization of C₂ F₄
B. Powder coating – Electrolysis of polymer resinssource.
C. Anodizing plating of ceramic layer on Al
D. Soap making Esterification of fatty acids
View Answer
A
50. A patient is administered a radioactive tracer that emits Gama (y)-rays and has a half-life of 6 hours. What will be the percentage of radioactivity remaining after 24 hours?
A. 6.25%
B. 12.5%
C. 25%
D. 50%
View Answer
A
REMEMEBER:
Solving sample papers is one of the most important things students must do during their preparation.
Why is this Exam Important?
Students who prepare seriously gain:
- Strong science fundamentals
- Better analytical thinking
- Confidence in practical work
- Experience with research projects
- Preparation for future Olympiads and competitive science exams
- Improved presentation and interview skills
Preparation Strategy for Class 6
1. Study the Textbooks Thoroughly
Focus mainly on:
- Class 6 Science
- Revise Classes 4 and 5 Science
2. Solve Previous Year Papers
This helps you understand:
- Question style
- Difficulty level
- Time management
3. Practice Science GK
Topics include:
- Famous scientists
- Space
- Environment
- Human body
- Animals and plants
- Everyday scientific facts
4. Perform Simple Experiments
For example:
- Floating and sinking
- Magnetism
- Plant growth
- Water filtration
- Air pressure
5. Improve Observation Skills
Practice:
- Diagrams
- Graphs
- Experimental setups
- Scientific instruments
