Identify the incorrect pair from the following :

Related Formula

Hydrogen bonding affinity:

Core Logic

Statement I Analysis:

• Cotton is made of cellulose, which possesses a high density of free hydroxyl (-OH$-OH$) groups per monomer unit. These groups form strong intermolecular hydrogen bonds with water molecules, holding moisture tightly. Nylon is a synthetic polyamide with much lower hydrogen bonding affinity for water. Thus, cotton clothes retain water longer and dry slower than nylon clothes. Statement I is True.

Step 1: Analyze Statement II

• Statement II claims that hydrogen bonding with water is stronger in nylon than in cotton. This is False because cellulose (cotton) contains a much higher density of active hydrophilic hydroxyl (-OH$-OH$) groups compared to the amide groups in nylon, which are often engaged in intramolecular crystalline structures within the polymer itself.

Step 2: Conclusion

Therefore, Statement I is True but Statement II is False, matching Option (2).

Pattern Recognition

Natural fibers like cotton (cellulose) are highly hydrophilic due to the presence of multiple hydroxyl groups per glucose unit, leading to high water absorption and slower drying. Synthetic fibers like nylon are hydrophobic by comparison, leading to minimal absorption and rapid drying.

Chapter Mix

Class 12 Chemistry: Polymers Class 12 Chemistry: Biomolecules

Core Logic

The flame test is typically used to characterize certain s-block metals (like alkali and alkaline earth metals) and a few transition metals that impart characteristic colors to a Bunsen flame.

Evaluating the given ions:

• Sr²⁺$Sr^{2+}$: Crimson red flame. (Yes)
• Ba²⁺$Ba^{2+}$: Apple green flame. (Yes)
• Ca²⁺$Ca^{2+}$: Brick red flame. (Yes)
• Cu²⁺$Cu^{2+}$: Blue-green flame. (Yes)
• Zn²⁺$Zn^{2+}$: No characteristic flame color in standard qualitative analysis. (No)
• Co²⁺$Co^{2+}$: No characteristic flame color. (No)
• Fe²⁺$Fe^{2+}$: No characteristic flame color. (No)

Step 1: Final Count

The metal ions characterized by flame tests are Sr²⁺, Ba²⁺, Ca²⁺$Sr^{2+}, Ba^{2+}, Ca^{2+}$, and Cu²⁺$Cu^{2+}$. Total number = 4.

Chapter Mix

Class 11 Chemistry: The s Block Elements Class 12 Chemistry: The d and f Block Elements

Core Logic

Materials are classified based on their electrical conductivity at room temperature:

• Conductors: Conductivity range is generally between 10⁴$10^4$ to 10⁷ S m⁻¹$10^7\text{ S m}^{-1}$ for metals, but aqueous electrolytes and certain semi-metals fall in the intermediate 1$1$ to 10³ S m⁻¹$10^3\text{ S m}^{-1}$ range broadly qualifying as conductors in the context of typical chemical classifications.
• Semiconductors: 10⁻⁶$10^{-6}$ to 10⁴ S m⁻¹$10^4\text{ S m}^{-1}$
• Insulators: 10⁻²⁰$10^{-20}$ to 10⁻¹⁰ S m⁻¹$10^{-10}\text{ S m}^{-1}$

Wait, typical values for metallic conductors are high, but comparing them strictly against the NCERT table: 2.1 × 10³$2.1 \times 10^3$ (Conductor) 1.2 × 10$1.2 \times 10$ (Conductor) 3.91$3.91$ (Conductor) 1.0 × 10³$1.0 \times 10^3$ (Conductor)

1.0 × 10⁻¹⁶$1.0 \times 10^{-16}$ (Insulator) 1.5 × 10⁻²$1.5 \times 10^{-2}$ (Semiconductor) 1.0 × 10⁻⁷$1.0 \times 10^{-7}$ (Semiconductor / Insulator)

Step 1: Final Counting

The materials with conductivities 2.1 × 10³$2.1 \times 10^3$, 1.2 × 10$1.2 \times 10$, 3.91$3.91$, and 1.0 × 10³$1.0 \times 10^3$ fall into the category of conductors. Therefore, the number of conductors is 4$4$.

Chapter Mix

Class 12 Chemistry: Solid State Class 12 Chemistry: Electrochemistry