1. How does vulcanization make natural rubber more durable?
[A] The long polymer chains are shortened
[B] The rubber loses water and sticky substances
[C] The short polymer chains are lengthened
[D] Cross links form between the polymer chains
Show Answer
Correct Answer: D [Cross links form between the polymer chains]
Notes:
Vulcanization introduces sulfur cross-links between poly-isoprene chains in natural rubber, restricting movement, which increases stiffness, elasticity, and durability. This chemical modification prevents rubber from becoming sticky or brittle, significantly improving its mechanical properties for industrial and commercial use.
2. In which of the following respects is white Portland cement different from ordinary gray Portland cement?
- The amount of chromium, manganese, and iron compounds is significantly less in white cement compared to gray cement.
- The setting behaviour and strength development of white cement is significantly improved compared to gray cement.
- Gypsum is used in making white cement but not in gray cement.
- Production of white cement consumes significantly more energy compared to gray cement.
Select the correct option from the codes given below:
[A] Only 2, 3 & 4
[B] Only 1, 2 & 3
[C] Only 1, 2 & 4
[D] Only 1 & 4
Show Answer
Correct Answer: D [Only 1 & 4]
Notes:
Statement 1 is correct: White cement has less chromium, manganese, and iron than gray cement. Statement 2 is incorrect: White and gray cement have similar setting and strength properties. Statement 3 is incorrect: Gypsum is used in both types. Statement 4 is correct: White cement production requires more energy due to special raw material and kiln conditions.
3. With reference to anhydrous ammonia used in industrial refrigeration, which of the following properties make it a useful chemical?
- Ammonia is non-toxic
- Ammonia has a high dipole moment
- Ammonia has high heat of vaporization
- Ammonia is non-corrosive to copper alloys
Select the correct option from the codes given below:
[A] Only 1 & 3
[B] Only 1, 2 & 3
[C] Only 2 & 3
[D] Only 3 & 4
Show Answer
Correct Answer: C [Only 2 & 3]
Notes:
Ammonia is widely used in industrial refrigeration due to its high dipole moment and high heat of vaporization, enabling efficient heat exchange. However, ammonia is toxic and also corrosive to copper alloys, making statements 1 and 4 incorrect. Therefore, only statements 2 and 3 correctly state properties making ammonia useful in this context.
4. Why a little pack of Silica Gel (granular beads of Silica made from Sodium Silicate) is packaged with many new items to control humidity and avoid spoilage or degradation?
[A] Silica gel molecules are hydrophilic with large surface area and so its molecules trap the moisture
[B] Silica gel is a Hygroscopic substance with large surface area so its molecules absorb the moisture.
[C] Silica gel molecules are with a portion that is charge-polarized and capable of hydrogen bonding, thus bonds with the water molecules
[D] The semi permeable pouch in which silica gel is placed absorbs the moisture which later reacts with water.
Show Answer
Correct Answer: B [ Silica gel is a Hygroscopic substance with large surface area so its molecules absorb the moisture.]
Notes:
The silica gel molecules have a large surface area because of the pores of around 2.4 nm. So, it absorbs the moisture. Hydrophilic products are polarized and Hydrophobic molecules which generally don’t catch water are NON polar.
5. Consider the following pairs:
- Strontium carbonate – Red fireworks
- Barium chloride – Green fireworks
- Copper chloride – Blue fireworks
- Sodium nitrate – Yellow fireworks
Which of the above pairs are correctly matched?
[A] Only 1 and 2
[B] 1, 2, 3 and 4
[C] 1, 2 and 3 only
[D] 2 and 3 only
Show Answer
Correct Answer: B [1, 2, 3 and 4]
Notes:
All listed pairs are correctly matched. Strontium carbonate produces red; barium chloride, green; copper chloride, blue; and sodium nitrate, yellow flame in fireworks. Metal salts in pyrotechnics impart characteristic colours—this is widely applied in fireworks manufacturing for visual effects.
6. Consider the following statements regarding Zeolites:
- Zeolites constitute a large group of natural and synthetic hydrated aluminium silicates.
- They are predominantly found in low-temperature metamorphic rocks.
Which of the above statements is/are correct?
[A] Only 1
[B] Only 2
[C] Both 1 and 2
[D] Neither 1 nor 2
Show Answer
Correct Answer: C [Both 1 and 2]
Notes:
Both statements are correct. Zeolites are indeed a group of natural and synthetic hydrated aluminum silicates known for their porous structure. They primarily occur in low-temperature metamorphic and volcanic rocks, where their unique properties make them significant for ion exchange, catalysis, and water purification processes.
7. With reference to hydrocarbons, consider the following statements:
- They do not have hydrogen-hydrogen bonds because there is no polarity in the bonds.
- They do not have hydrogen-hydrogen bonds because the electronegativity difference is too large.
Which of the above statements is/are correct?
[A] Only 1
[B] Only 2
[C] Both 1 & 2
[D] Neither 1 nor 2
Show Answer
Correct Answer: A [Only 1]
Notes:
Hydrocarbons consist of carbon-carbon and carbon-hydrogen bonds. These bonds are only weakly polar due to a small electronegativity difference (0.4) between carbon and hydrogen, so no significant partial charges form. Therefore, there is no polarity and thus no hydrogen bonding. The electronegativity difference is not too large; statement 2 is incorrect.
8. Consider the following:
- Gold is classified as a metal
- Sulphur is classified as a non-metal
- Silicon is classified as a metalloid
Which of the above statements is / are correct?
[A] Only 1 and 2
[B] Only 3
[C] Only 2 and 3
[D] 1, 2 and 3
Show Answer
Correct Answer: D [1, 2 and 3]
Notes:
All the given statements are correct. Gold is a well-known metal, sulphur is a typical non-metal, and silicon is correctly classified as a metalloid due to its intermediate properties between metals and non-metals. Thus, all three are correctly matched according to their standard chemical classifications.
9. Consider the following fertilizers:
- Urea
- Anhydrous Ammonia
- Muriate of potash
At present, which of the above is / are under price control by government?
[A] Only 1 & 2
[B] Only 1 & 3
[C] Only 2 & 3
[D] 1, 2 & 3
Show Answer
Correct Answer: A [Only 1 & 2 ]
Notes:
At present, only three fertilizers viz. Urea, Zincated Urea & Anhydrous Ammonia are under price control.
10. Which of the following statements regarding global energy production by Nuclear Fission and Nuclear Fusion are correct?
- In almost all nuclear plants worldwide, nuclear fission is used for producing energy.
- Nuclear fission produces nuclear fusion byproducts, and nuclear fusion produces nuclear fission byproducts.
Select the correct option from the codes given below:
[A] Only 1 is correct
[B] Only 2 is correct
[C] Both 1 & 2 are correct
[D] Neither 1 nor 2 is correct
Show Answer
Correct Answer: A [Only 1 is correct]
Notes:
Nuclear fission is used in all commercial nuclear power plants for energy production. Nuclear fusion remains experimental and is not utilized for global energy generation. Fission produces fission products, not fusion byproducts. Fusion reactions produce different byproducts and do not generate fission products. Thus, only statement 1 is correct.
