SSC JE Chemistry Questions with Detailed Solutions

Correct Answer: (C) Wood is an insulator and does not heat up

Explanation:

• Wood is a poor conductor of heat, which means it does not transfer heat quickly from a hot pan to your hand.
• Therefore, using a wooden spoon while cooking is safer because it remains cool to touch, unlike metallic spoons that conduct heat rapidly and can cause burns.

Information Booster:

• Metallic spoons are good conductors of heat, so they become hot very quickly when left in a hot pan.
• Wooden spoons:
• Do not react chemically with food
• Do not scratch non-stick or delicate cookware
• Are durable and eco-friendly
• Other common insulators in the kitchen: Plastic spatulas, silicone utensils

Other Options:

• A (Wood is a good conductor of heat) – Incorrect; wood is an insulator, not a conductor
• B (Wood adds flavor to food) – Not generally true; flavor addition is negligible
• D (Wood helps food cook faster) – Incorrect; cooking speed depends on heat source, not the utensil material.

Correct Answer: (C) Summation of all the atomic masses of all the atoms within the formula

Explanation:

• The formula unit mass (or molecular mass for molecules) is calculated by adding the atomic masses of all the atoms present in a compound’s formula.
• This gives the mass of one formula unit of an ionic compound (like NaCl) or one molecule of a molecular compound (like H₂O).

Information Booster:

• Steps to Calculate Formula Unit Mass:
1. Identify all atoms in the chemical formula
2. Find the atomic mass of each atom (from periodic table)
3. Multiply the atomic mass by the number of atoms of that element in the formula
4. Add the masses of all elements together
• Example: Water (H₂O)

• Hydrogen: 1 × 2 = 2
• Oxygen: 16 × 1 = 16
• Formula unit mass = 2 + 16 = 18 u

Correct Answer: (C) D – Changing the colour of the matter

Explanation:

• Changes in the state of matter (solid, liquid, gas) are affected by:
• Kinetic energy of particles – Higher kinetic energy can lead to melting or evaporation.
• Temperature – Directly influences particle energy and phase changes.
• Pressure – Can affect boiling and melting points, especially in gases and liquids.
• Colour of the matter has no effect on its physical state; it only affects how the matter appears visually.

Information Booster:

• Phase changes and factors affecting them:
• Melting/Freezing – Temperature and pressure dependent
• Boiling/Condensation – Temperature and pressure dependent
• Sublimation/Deposition – Temperature and pressure dependent
• Kinetic Molecular Theory:
• Particle motion increases with heat → solid → liquid → gas
• Particle motion decreases with cooling → gas → liquid → solid

Correct Answer: (A) Sodium metabisulphite

Explanation:

• Sodium metabisulphite (Na₂S₂O₅) is a sulphur-containing preservative commonly used in the food industry.
• In meat products like fresh sausages and burgers, it helps to:
• Prevent microbial growth
• Inhibit enzymatic browning
• Increase shelf life by slowing spoilage

Information Booster:

• Other uses of Sodium Metabisulphite:
• Preserving fruits, vegetables, and beverages
• Used in wine and beer making as a reducing agent
• Acts as an antioxidant in various food products
• Precautions:
• Can cause allergic reactions in sensitive individuals
• Must be used within permissible limits specified by food safety authorities

Other Options:

• B (Sodium polysulfides) – Used in rubber and chemical industries, not meat preservation
• C (Sodium thiosulfate) – Used in photography and medical treatments, not for food preservation
• D (Sodium phenyl sulfide) – Not used as a food preservative

The correct answer is (B) Latent heat of fusion

Explanation:
• The Latent Heat of Fusion is the amount of heat energy required to change 1 kg of a solid into liquid at its melting point without any rise in temperature.
• The word 'Latent' means hidden.

Information Booster:
• For ice, the latent heat of fusion is 334 kJ/kg.

Additional Knowledge:
• Latent Heat of Vaporization is for the liquid-to-gas change.

The correct answer is (D) Sodium bicarbonate

Explanation:
• Sodium Bicarbonate (NaHCO₃), commonly known as Baking Soda, reacts with acids (like lemon juice or vinegar) to release Carbon Dioxide gas.
• This reaction causes dough/batter to rise.

Information Booster:
• Baking Powder contains Baking Soda plus a dry acid (like tartaric acid).
• It is a mild base.

Additional Knowledge:
• Sodium Nitrate (Option C) is used in fertilizers and explosives.

The correct answer is (A) Limewater

Explanation:
• Calcium Hydroxide [Ca(OH)₂] in a saturated aqueous solution is commonly known as Limewater.
• It turns milky when Carbon Dioxide (CO₂) is passed through it.

Information Booster:
• Solid Calcium Hydroxide is called Slaked Lime.
• Quick Lime is Calcium Oxide (CaO).

Additional Knowledge:
• Carbonated water contains dissolved CO₂ (Carbonic Acid).

Correct Answer: (D) NaHCO₃

Explanation:

• Baking soda is chemically known as sodium bicarbonate, and its formula is NaHCO₃.
• It is commonly used in cooking, baking, cleaning, and as an antacid.
• When heated, baking soda decomposes to produce carbon dioxide (CO₂), water, and sodium carbonate (Na₂CO₃), which helps in leavening baked goods.

Information Booster:

• Uses of Baking Soda:
• Culinary: Leavening agent in cakes and bread
• Medicinal: Neutralizes stomach acid, used in antacids
• Cleaning: Removes stains and odors
• Fire safety: Can be used in small grease fires to suppress flames

Other Options:

• A (Na₂CO₃·10H₂O) – This is washing soda, not baking soda.
• B (NaOH) – Sodium hydroxide, a strong alkali, used in soap making and industrial applications.
• C (CaOCl₂) – Calcium hypochlorite, used as bleaching powder and disinfectant.

Correct Answer: (A) Naphthalene 

Explanation:

• Sublimation is the process in which a substance changes directly from solid to gas without passing through the liquid state.
• Naphthalene, commonly used in mothballs, is a classic example of a sublimable substance. It vaporizes on heating and can condense back to solid upon cooling.

Information Booster:

• Other Sublimable Substances: Camphor, iodine, dry ice (solid CO₂).
• Applications of Sublimation:
• Purification of solids (e.g., iodine and naphthalene)
• Moth repellents (naphthalene)
• Freeze-drying of food
• Chemical Property: Sublimation occurs because the substance has sufficient vapor pressure at a temperature below its melting point.

Other Options:

• B (Rust) – Iron oxide; does not sublimate.
• C (Alum) – Does not undergo sublimation under normal conditions.
• D (Chalk Powder) – Mainly calcium carbonate; does not sublimate.

Correct Answer: (D) Chloroform 

Explanation:

• Chloroform is a colorless liquid with the chemical formula CHCl₃.
• It evaporates quickly at room temperature due to its relatively high volatility, turning into gas.
• Historically, chloroform was used as an anaesthetic, but due to its toxicity, its medical use has decreased.

Information Booster:

• Properties of Chloroform:
• Molecular formula: CHCl₃
• Boiling point: 61.2°C
• Odor: Sweet, ether-like
• Uses: Solvent in laboratories, previously used as an anaesthetic
• Safety Note: Highly toxic and can damage the liver and nervous system upon exposure.

Other Options:

• A (Ethanol) – Alcohol, formula C₂H₅OH, flammable, slower evaporation.
• B (Acetone) – Solvent, formula (CH₃)₂CO, highly volatile, but not CHCl₃.
• C (Ammonia) – Gas at room temperature, formula NH₃, not a liquid like CHCl₃.

Answer: A. Group 11 

Explanation:

• Silver (Ag) is a metallic element that belongs to Group 11 of the periodic table.
• Group 11 elements are also known as the coinage metals, which include Copper (Cu), Silver (Ag), and Gold (Au).
• These metals are known for their high electrical conductivity, malleability, and resistance to corrosion.
• Silver, in particular, is widely used in jewelry, coins, electronics, and photography.

Information Booster:

• Group 11 elements typically have a +1 oxidation state in their compounds.
• Silver has the highest electrical and thermal conductivity among all metals.
• Unlike some other metals, silver does not easily react with oxygen, which is why it remains shiny over time.

Incorrect Options:

• Group 15 – contains nitrogen, phosphorus, arsenic, antimony, and bismuth (mostly non-metals/metalloids).
• Group 7 – contains manganese, technetium, rhenium.
• Group 3 – contains scandium, yttrium, and lanthanides/actinides elements.

The correct answer is (C) nucleons.

Explanation:

• The nucleus of an atom is made up of two types of particles:
• Protons (positively charged)
• Neutrons (neutral)
• Together, protons and neutrons are called nucleons.
• These nucleons are held tightly by the strong nuclear force, one of the four fundamental forces of nature, which is much stronger than the electrostatic repulsion between protons.
• The number of protons (atomic number, Z) determines the element, while the total number of nucleons (mass number, A = protons + neutrons) determines its atomic mass.

Information Booster:

• Electrons are not part of the nucleus; they revolve around the nucleus in different energy levels (shells).
• Isotopes are atoms of the same element with the same number of protons but different numbers of neutrons (hence different nucleon numbers). Example: Carbon-12 and Carbon-14.
• Ions are atoms or molecules that have gained or lost electrons, giving them a net electric charge.

Additional Knowledge on Options:
(A) Isotopes – Variants of an element with different neutron counts.
(B) Ions – Charged atoms (positive or negative).
(C) Nucleons – Correct; protons + neutrons in the nucleus.
(D) Electrons – Negatively charged particles orbiting the nucleus.

The correct answer is (D) Sodium hydroxide.

Explanation:

• Saponification is the process in which fats or oils (esters of fatty acids) are hydrolyzed by an alkali to produce glycerol and soap (salts of fatty acids).
• The alkali commonly used is sodium hydroxide (NaOH), also known as caustic soda.
• When NaOH reacts with fats, it neutralizes the fatty acids, converting them into sodium salts (soap).
• If potassium hydroxide (KOH) is used instead, the result is a softer soap (like liquid soaps).

Reaction (simplified):
Fat (triglyceride) + Sodium hydroxide → Glycerol + Soap (sodium salt of fatty acid)

Information Booster:

• Soaps are surfactants – they reduce the surface tension of water, allowing it to remove dirt and grease effectively.
• The hydrophilic end of soap dissolves in water, while the hydrophobic end dissolves in oil/grease, helping wash them away.
• Saponification is also used in making biodiesel and cosmetics.

Additional Knowledge on Options:
(A) Sodium fluoride – Used in toothpaste and water fluoridation, not for soap making.
(B) Sodium acetate – A salt used in food as a preservative and buffer, not for saponification.
(C) Sodium chlorate – A strong oxidizing agent, used in herbicides and explosives.
(D) Sodium hydroxide – Correct; alkali used in saponification to make soap.

The correct answer is (B) CaO

Explanation:

To find the chemical formula of a compound, we balance the valencies (combining capacities) of the constituent elements.

•        Calcium (Ca) is a metal from Group 2 of the Periodic Table.

•         ◦ Its valency is 2+, meaning it loses two electrons to become Ca²⁺.

•        Oxygen (O) is a non-metal from Group 16.

•         ◦ Its valency is 2−, meaning it gains two electrons to become O²⁻.

•        When Ca²⁺ and O²⁻ combine:

•        Their charges are equal and opposite (+2 and –2), so only one atom of each is needed to balance the charges.

•        Thus, the simplest and correct chemical formula is CaO (in a 1:1 ratio).

Information Booster:

•        CaO (Calcium oxide) is commonly known as quicklime.

•        It is a white, alkaline, crystalline solid at room temperature.

•        It is used in cement, metallurgy, and soil treatment for its neutralizing properties.

•        CaO reacts exothermically with water to form calcium hydroxide (Ca(OH)₂), a process called slaking.

Additional Knowledge:

(A) Ca₂O₂ – Incorrect. This formula is not in its simplest ratio; it simplifies to CaO.

(C) CaO₂ – Incorrect. This would imply calcium peroxide, where oxygen has a valency of –1 (not applicable here).

(D) Ca₂O – Incorrect. This suggests an imbalance in charge (net +2), which is chemically unstable.

Hence, the correct and simplified chemical formula is CaO.

The correct answer is (C) Lemon juice.

Explanation:

• Lemon juice has a pH between 2 and 3, making it an acidic food item. The high acidity is due to the presence of citric acid, which is responsible for its tart taste.
• Foods and liquids with a pH below 7 are considered acidic, and lemon juice is one of the most common examples of highly acidic food.

Information Booster:

• The pH scale ranges from 0 to 14, where a pH of 7 is neutral (like pure water). Anything below 7 is acidic, and anything above 7 is alkaline (basic).
• Lemon juice, with its low pH, can be used to balance sweetness in cooking and as a natural preservative due to its acidity.
• Citric acid in lemon juice can also aid digestion and is commonly used for its antioxidant properties.

Why other options are incorrect:

• A) Apple juice: Apple juice typically has a pH of about 3 to 4, making it less acidic than lemon juice.
• B) Blackberry juice: Blackberry juice has a pH of around 3 to 3.5, which is also acidic but not as much as lemon juice.
• D) Tomato juice: Tomato juice has a pH of about 4 to 4.5, which is also acidic but falls outside the 2-3 pH range.