SSC JE Science Questions with Detailed Solutions

Correct Answer: (B) Acetic acid

Explanation:

• Acetic acid (CH₃COOH) is a simple monocarboxylic acid containing two carbon atoms.
• It is also known as ethanoic acid and is the main component of vinegar.
• Being a monocarboxylic acid, it contains one carboxyl (-COOH) group.

Information Booster:

• Other acids listed:
• Capric acid (C10H20O2) – 10-carbon saturated fatty acid, found in coconut oil
• Palmitic acid (C16H32O2) – 16-carbon saturated fatty acid, common in fats and oils
• Valeric acid (C5H10O2) – 5-carbon saturated fatty acid, also called pentanoic acid
• Uses of Acetic Acid:
• Food preservative (vinegar)
• Industrial production of acetic anhydride and esters
• Laboratory solvent and reagent

Other Options:

• A (Capric acid) – 10 carbons; not two
• C (Palmitic acid) – 16 carbons; not two
• D (Valeric acid) – 5 carbons; not two

Correct Answer: (C) 1.602 × 10⁻¹⁹ joules 

Explanation:

• 1 electron volt (eV) is defined as the energy gained or lost by an electron when it moves through an electric potential difference of 1 volt.
• Formula: 1 eV = charge of electron × 1 volt = 1.602 × 10⁻¹⁹ coulombs × 1 volt = 1.602 × 10⁻¹⁹ joules.
• Electron volts are commonly used in atomic and nuclear physics because the energies of particles at these scales are extremely small compared to everyday energy units like joules.

Information Booster:

• Applications of eV:
• Measuring energy of electrons, protons, and photons in atomic and nuclear physics
• Used in particle accelerators, semiconductors, and X-ray spectroscopy
• Conversions:
• 1 keV (kilo-electron volt) = 10³ eV
• 1 MeV (mega-electron volt) = 10⁶ eV
• 1 GeV (giga-electron volt) = 10⁹ eV

The correct answer is (A) They had rectilinear motion

Explanation:
• Motion along a straight line is called rectilinear motion.
• Objects falling freely under the influence of gravity (without significant wind resistance deviating them) follow a straight vertical path towards the ground.

Information Booster:
• Other examples of rectilinear motion include a car moving on a straight road or a bullet fired from a gun.

Additional Knowledge:
• Curvilinear motion (Option B): Motion along a curved path (e.g., a stone thrown at an angle).
• Gravity free motion (Option D): This occurs in space where gravitational forces are negligible.

The correct answer is (B) GM/R²

Explanation:
• The acceleration due to gravity (g) is derived from Newton's Law of Universal Gravitation.
• Force F = GMm/R² and F = mg.
• Equating them: mg = GMm/R², which gives g = GM/R².

Information Booster:
• The value of 'g' on Earth's surface is approximately 9.8 m/s².
• 'G' is a universal constant, while 'g' varies depending on location (poles vs equator).

Additional Knowledge:
• 'g' decreases with altitude and depth.

The correct answer is (C) 3u

Explanation:
• For an object moving with uniform acceleration, the Average Velocity is given by the formula: (Initial Velocity + Final Velocity) / 2.
• Here, Initial Velocity = u, Final Velocity = 5u.
• Average Velocity = (u + 5u) / 2 = 6u / 2 = 3u.

Information Booster:
• This formula holds true only when acceleration is constant.

Additional Knowledge:
• The equation of motion is v = u + at.

Correct Answer: (A) 0.001 AMP

Explanation:

• A milliampere (mA) is a unit of electric current equal to one-thousandth of an ampere (A).
• In other words, 1 milliampere = 0.001 ampere.
• Milliampere is commonly used to measure small currents in electrical and electronic devices, as well as in medical instruments.

Information Booster:

• 1 Ampere (A) = 1000 milliamperes (mA)
• 1 microampere (µA) = 0.000001 A
• Applications of milliamp measurement:
• Battery-powered devices
• Electronic circuits
• Current monitoring in medical devices

Correct Answer: (B) 80 joules 

Explanation:

• Given:
• Mass of cricket ball = 160 grams = 0.16 kg
• Height = 50 metres
• Acceleration due to gravity = 10 m/s²
• Step 1: Use the formula
• Kinetic energy just before hitting the ground = Potential energy at height
• KE = mass × gravity × height
• Step 2: Substitute values
• KE = 0.16 × 10 × 50
• 10 × 50 = 500
• 0.16 × 500 = 80
• Step 3: Conclusion
• KE = 80 joules

Information Booster:

• This calculation assumes no air resistance.
• Demonstrates the law of conservation of mechanical energy:
• Potential energy at the top converts entirely into kinetic energy at the bottom.
• Useful for understanding free-fall motion in physics.

Correct Answer: (C) Increase in surface area reduces the force exerted 

Explanation:

• When you carry a heavy bag with thin handles, the force is concentrated on a very small area of your hand, which makes it painful and difficult.
• Covering the handles with a thick piece of cloth increases the contact area between the hand and the handle.
• The same weight (force) is now distributed over a larger area, reducing the pressure on your hand and making it easier and more comfortable to carry.

Information Booster:

• Pressure Formula: Pressure = Force ÷ Area
• Practical Application:
• Shoulder straps of bags are usually wide and padded to reduce pressure.
• Snowshoes work on the same principle to prevent sinking by increasing surface area.
• Significance: Shows how force distribution affects comfort and usability in daily life.

Other Options:

• A (Handles become stronger) – Incorrect; the cloth does not strengthen the handles.
• B (Cloth is colourful) – Incorrect; color has no effect on carrying.
• D (Chances of tearing are eliminated) – Only partially true; main reason is pressure reduction, not tearing prevention.

Correct Answer: (B) Combination of water and our body is a good conductor of electricity.

Explanation:

• Electricity flows easily through conductors, and human body contains water and salts, making it a good conductor.
• If you touch an electric switchboard with wet hands, the risk of electric shock increases because water reduces the resistance of your skin, allowing current to pass more easily through your body.
• This can lead to serious injuries or even fatalities.

Information Booster:

• Safety Tips Around Electricity:
• Always dry your hands before touching any electrical appliance or switch.
• Use insulated footwear to reduce risk of shocks.
• Ensure switchboards and wires are properly insulated.
• Avoid using damaged or exposed wires.
• Why Wet Hands Are Dangerous:
• Skin resistance drops from around 100,000 ohms (dry) to 1,000 ohms (wet), greatly increasing current flow.
• Conclusion: Always ensure your hands are dry before operating any electrical switch to prevent electric shock.

Other Options:

• A (Water can erode the switchboard) – Incorrect; corrosion is slow and not the main danger.
• C (Wet hands can fade away the colour coat of the switchboard) – Incorrect; cosmetic effect, not safety hazard.
• D (Wet hands might slip from the switch) – Minor concern; the danger is electric shock.

The correct answer is (A) Electric Charge.

Explanation:

• The SI unit of electric charge is the coulomb (C), named in honor of Charles Augustin de Coulomb, a French physicist.
• Coulomb is famous for Coulomb’s Law, which describes the electrostatic force between two point charges.
• One coulomb is defined as the amount of charge transported by a constant current of one ampere in one second.

Information Booster:

• Charles Augustin Coulomb (1736–1806) conducted experiments on electrostatic forces and magnetism, laying the foundation of electrostatics.
• Other related SI units named after scientists include:
• Volt (V) → Alessandro Volta
• Ampere (A) → André-Marie Ampère
• Ohm (Ω) → Georg Ohm

Why other options are incorrect:

• B. Electric Power: The SI unit is watt (W), named after James Watt.
• C. Electric Field: Measured in volts per meter (V/m), not named after Coulomb.
• D. Current Density: Measured in amperes per square meter (A/m²), not named after Coulomb.

Correct Answer: (D) Pressure

Explanation:

• Pascal (Pa) is the SI unit of pressure.
• Pressure is defined as the force applied per unit area.
• 1 Pascal is equal to a force of 1 Newton applied uniformly over an area of 1 square meter.

Information Booster:

• Formula for Pressure: Pressure = Force / Area
• Other SI units:
• Mass density – kg/m³
• Energy – Joule (J)
• Power – Watt (W)
• Pascal is widely used in physics, engineering, and meteorology to measure pressure in gases and liquids.

So, the SI unit of pressure is Pascal (Pa).

The correct answer is (A) lower frequency and higher amplitude.

Explanation:

• Pitch of a sound is determined by its frequency:
• Low pitch → low frequency
• High pitch → high frequency
• Loudness of a sound is determined by its amplitude:
• Higher amplitude → louder sound
• Lower amplitude → softer sound
• Therefore, a low-pitched but louder sound has a low frequency and a high amplitude.

Information Booster:

• Frequency (f): Number of vibrations per second measured in Hertz (Hz).
• Amplitude: Maximum displacement of particles in the medium; determines intensity and loudness.
• Examples:
• A bass drum produces a low-pitched, loud sound → low frequency, high amplitude.
• A whistle produces a high-pitched, soft sound → high frequency, low amplitude.

Why other options are incorrect:

• (B) higher frequency and lower amplitude: Would be a high-pitched, soft sound.
• (C) lower frequency and lower amplitude: Would be low-pitched but soft, not loud.
• (D) higher frequency and higher amplitude: Would be high-pitched and loud, not low-pitched.

The correct answer is (A) Chloroplast.

Explanation:

• Chloroplasts are the organelles in plant cells where photosynthesis takes place.
• They contain the green pigment chlorophyll, which captures sunlight and uses it to convert carbon dioxide and water into glucose and oxygen.
• Photosynthesis occurs in two stages:
1. Light-dependent reactions – take place in the thylakoid membranes, producing ATP and NADPH.
2. Calvin cycle (light-independent reactions) – occurs in the stroma, where glucose is synthesized.

Information Booster:

• Chloroplasts are known as semi-autonomous organelles because they contain their own DNA and ribosomes, allowing them to produce some of their own proteins.
• They are part of the plastid family, which also includes chromoplasts (pigments other than green) and leucoplasts (storage).
• Photosynthesis equation (simplified):
  Carbon dioxide + Water + Sunlight → Glucose + Oxygen

Additional Knowledge on Options:
(B) Mitochondrion – Known as the “powerhouse of the cell,” produces ATP through cellular respiration.
(C) Lysosome – Contains digestive enzymes for breaking down waste and cellular debris.
(D) Peroxisome – Involved in breaking down fatty acids and detoxifying harmful substances.

The correct answer is (C) Lysosome.

Explanation:

• Lysosomes are small, membrane-bound organelles in eukaryotic cells that contain hydrolytic enzymes capable of breaking down cellular waste, worn-out organelles, and foreign materials like bacteria.
• They are often called the “suicidal bags of the cell” because, if ruptured, their enzymes can digest the entire cell.
• Lysosomes play a vital role in intracellular digestion, recycling of cell components (autophagy), and defense against pathogens.

Information Booster:

• The enzymes inside lysosomes work best in an acidic environment (pH ~5).
• Lysosomes are formed from Golgi apparatus vesicles.
• Malfunctioning lysosomes can lead to lysosomal storage disorders, such as Tay-Sachs disease.

Additional Knowledge on Options:
(A) Nucleus – Controls cell activities and stores genetic material (DNA).
(B) Mitochondrion – Known as the powerhouse of the cell, produces ATP through cellular respiration.
(C) Lysosome – Contains digestive enzymes for waste breakdown.
(D) Vacuole – Stores water, nutrients, and waste products; in plant cells, it maintains turgor pressure.

The correct answer is (B) Carbohydrates.

Explanation:

• Nutrients are classified into macronutrients and micronutrients.
• Macronutrients are nutrients required by the body in large amounts to provide energy and structural components. They include:
• Carbohydrates
• Proteins
• Fats
• Water
• Carbohydrates are the body’s primary energy source, broken down into glucose to fuel cells, tissues, and organs.
• They provide 4 calories per gram and are essential for physical activity, brain function, and metabolic processes.

Information Booster:

• Micronutrients, on the other hand, are required in small amounts and include vitamins and minerals.
• Antioxidants (like Vitamin C, Vitamin E, and selenium) protect the body from free radical damage, but they are micronutrients, not macronutrients.
• Balanced nutrition requires both macronutrients (for energy and growth) and micronutrients (for regulation and protection).

Additional Knowledge on Options:
(A) Vitamins – Micronutrients, required in small amounts for metabolic regulation.
(B) Carbohydrates – Macronutrient, primary energy provider.
(C) Minerals – Micronutrients, e.g., calcium, iron, zinc.
(D) Antioxidants – Protective compounds, usually vitamins/minerals, hence micronutrients.