BPSC CCE Prelims
General Science Previous Year Questions (PYQs)
Solved Previous Year Questions (PYQs) for General Science in BPSC CCE Prelims in English & Hindi Medium.
Chapter Breakdown: Scroll →
What is the law in which under the same above conditions of temperature and pressure, equal volumes of all gases contain equal number of molecules?
Detailed Explanation:
Avogadro's law states that under the same temperature and pressure, equal volumes of all gases contain equal number of molecules.
- Core Principle: Discovered by Amedeo Avogadro (1812), this fundamental gas law directly matches the question's description.
- Therefore, Avogadro's law is the correct answer, making Option 3 correct.
The 'theory of relativity' is presented by which scientist?
Detailed Explanation:
The Theory of Relativity was formulated by Albert Einstein in two parts: Special Relativity (1905) and General Relativity (1915).
- Special Relativity: Established that the speed of light is constant and the laws of physics are the same for all non-accelerating observers.
- General Relativity: Described gravity as the curvature of spacetime caused by mass and energy, replacing Newtonian gravity.
- Therefore, Albert Einstein is the scientist who presented the theory of relativity, making Option 4 the correct answer.
Due to temperature variation along a conductor, potential variation occurs along it. This phenomenon is known as
Detailed Explanation:
The Thomson effect describes the generation of electromotive force (EMF) in a single conductor due to a temperature gradient along its length.
- Core Distinction: Unlike the Seebeck effect (requiring two dissimilar metals), Thomson effect occurs in a single homogeneous conductor with varying temperature.
- Mechanism: Electrons diffuse from hot to cold regions, creating a potential difference proportional to the temperature gradient.
- Therefore, potential variation due to temperature variation in a single conductor is the Thomson effect, making Option 4 the correct answer.
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A person standing in front of a mirror finds his image larger than himself This implies that the mirror is
Detailed Explanation:
A concave mirror produces a magnified (larger) virtual image when the object is placed between the pole and focus—commonly seen in makeup/shaving mirrors.
A plane mirror always produces same-size images, a convex mirror always produces diminished images, and a cylindrical mirror with bulging side outwards distorts rather than uniformly magnifies.
Therefore, only a concave mirror produces a larger image when the person stands close enough, making Option 1 the correct answer.
A fan produces a feeling of comfort during the hot weather because
Detailed Explanation:
A fan creates air movement that accelerates the evaporation of perspiration from our skin. This evaporation is an endothermic process that absorbs heat from the body, producing a cooling sensation.
The fan does not supply cool air (it merely circulates room-temperature air), nor does it significantly alter body heat radiation or air conductivity—it purely enhances evaporative cooling.
Therefore, perspiration evaporates rapidly, making Option 4 the correct answer.
Twinkling of stars in clear sky during nighttime can be explained with
Detailed Explanation:
Stellar twinkling (or scintillation) occurs because starlight passes through Earth's atmosphere with continuously varying refractive index due to turbulent air layers of different temperatures and densities. This causes the light path to bend unpredictably, making stars appear to twinkle.
Reflection involves bouncing back of light, polarization relates to light wave orientation, and interference involves superposition of waves—none explain atmospheric twinkling.
Therefore, refraction of light is the correct physical phenomenon, making Option 1 the correct answer.
Hydrogen bomb is based on the principle of
Detailed Explanation:
A hydrogen bomb (thermonuclear weapon) derives its massive explosive energy from nuclear fusion, where light atomic nuclei (deuterium and tritium) combine at extremely high temperatures to form heavier nuclei, releasing enormous energy.
This fusion process is uncontrolled and instantaneous, creating a runaway chain reaction that produces the bomb's devastating yield. A fission bomb (atomic bomb) is used as a trigger to generate the extreme heat and pressure required to initiate the fusion reaction.
Therefore, hydrogen bombs operate on uncontrolled fusion reactions, making Option 2 the correct answer.
Food gets cooked faster in a pressure cooker because
Detailed Explanation:
In a pressure cooker, the sealed environment increases internal pressure, which raises the boiling point of water above the normal 100°C (at atmospheric pressure). Water boils at a higher temperature (~120°C), transferring more heat energy to food, cooking it faster.
Options 1 and 3 incorrectly state boiling occurs at low temperature, while option 4 wrongly claims low pressure inside the cooker.
Therefore, water boils at high temperature due to high pressure, making Option 2 the correct answer.
If the doors of a refrigerator are left open for few hours, then the room temperature will
Detailed Explanation:
A refrigerator operates on the Second Law of Thermodynamics: it removes heat from inside and releases it (plus compressor work energy) outside. With doors open, heat expelled into the room exceeds heat absorbed from the room, causing a net temperature increase.
The compressor converts electrical energy into heat, adding extra thermal energy to the room. The cooling effect is localized and temporary, while the heating effect is continuous and distributed.
Therefore, the room temperature will increase, making Option 2 the correct answer.
A piece of ice is floating in a beaker containing water up to its brim. When whole of the ice melts
Detailed Explanation:
When ice floats in water, it displaces a volume of water equal to its own weight. By Archimedes' principle, the mass of displaced water equals the mass of the ice.
When the ice melts, it converts into water of exactly the same mass and occupies the same volume as the water it originally displaced. Therefore, the water level remains unchanged.
Therefore, the water level will not change, making Option 4 the correct answer.
Which of the following is not correctly matched?
Detailed Explanation:
Galvanometer measures small electric currents and detects current direction using needle deflection; it does not measure electric resistance.
Voltmeter measures potential difference, Ammeter measures electric current, and Potentiometer measures electromotive force—all correctly matched.
Therefore, Galvanometer-Electric resistance is incorrectly matched, making Option 4 the correct answer.
If a feather, a rubber ball and a wooden ball are falling freely simultaneously from the same height in vacuum, then
Detailed Explanation:
In a vacuum, all objects fall with the same acceleration (g = 9.8 m/s²) regardless of mass or composition, as demonstrated by Galileo's principle. Without air resistance, a feather, rubber ball, and wooden ball experience identical downward acceleration.
Air resistance normally causes lighter objects like feathers to fall slower on Earth, but in vacuum conditions this factor is completely eliminated, making mass and material properties irrelevant to fall time.
Therefore, all three objects reach the ground simultaneously, making Option 4 the correct answer.
When a soap film on the water is seen in the daytime, it shows beautiful colours. This phenomenon is due to
Detailed Explanation:
Soap film has two surfaces (top and bottom) that reflect light. When white light hits these surfaces, waves reflected from the top and bottom surfaces overlap and interfere, causing certain wavelengths to cancel out and others to amplify, producing the vibrant colours observed.
Diffraction occurs when light bends around edges, refraction is bending due to medium change, and polarization restricts light vibrations to one plane—none explain the colour pattern in soap films.
Therefore, interference of light is responsible for soap film colours, making Option 4 the correct answer.
The mass number of a nucleus is
Detailed Explanation:
The mass number (A) of a nucleus is defined as the sum of protons and neutrons in the nucleus. It is a count (dimensionless integer), not the actual mass in kilograms or atomic mass units.
Option 2 incorrectly states "total mass" (which would have units); Option 3 is false—mass number is close to but not always more than atomic weight; Option 4 is absurd—mass number is always greater than atomic number (Z).
Therefore, Option 1 is the correct answer.
Which of the following is the main ingredient of cement?
Detailed Explanation:
Cement is manufactured using multiple key ingredients, making Option 5 the correct choice. The primary component is limestone (~60–65%), which provides calcium oxide. Silica clay (~20–25%) supplies silica, alumina, and iron oxide. Gypsum (~3–5%) is added post-burning to regulate setting time.
Since limestone, silica clay, and gypsum are all essential ingredients—not just one—the answer cannot be a single option.
Therefore, more than one ingredient is correct, making Option 5 the correct answer.