Iron is classified as a micronutrient, required in smaller amounts compared to macronutrients.

Calcium is classified as a secondary macronutrient, important for cell wall structure and stability.

Avoiding contractions helps maintain a formal tone, which is essential for academic writing in the UPSC Mains essays.

Fluorine is a halogen and is found in Group 17 of the periodic table.

Sodium is in period 3 of the periodic table.

Aluminium commonly forms a stable +3 oxidation state in its compounds.

Tin (Sn) is known for forming a stable +4 oxidation state.

Copper (Cu) is known for forming complex ions due to its ability to coordinate with ligands.

Copper (Cu) is known for its ability to form complex ions due to its d-orbitals.

Platinum (Pt) is widely known for its catalytic properties in various chemical reactions.

Nitrogen (N) has the configuration 1s2 2s2 2p3, which has a half-filled p subshell.

Potassium is an alkali metal and typically forms a +1 ion.

Sodium is an alkali metal and readily loses an electron to form a cation.

Chlorine (Cl) is a non-metal and is most likely to form covalent bonds.

Fluorine (F) is highly electronegative and readily forms anions (F-).

Chlorine is most likely to form an ionic bond with sodium as it readily accepts an electron to achieve a stable electron configuration.

Sodium is most likely to form an ionic bond as it readily loses an electron to form Na+.

Sodium is most likely to form an ionic bond as it readily loses an electron to form Na+.

Chlorine (Cl) is a non-metal and tends to form covalent bonds.

Aluminum is a metal, while silicon, boron, and germanium are metalloids.

Sodium is an s-block element, while Boron, Carbon, and Nitrogen are p-block elements.

Zinc (Zn) is not considered a transition metal because it does not have an incomplete d-subshell in its elemental state.

Aluminum (Al) is not an alkali metal; it is a post-transition metal.

Aluminum (Al) is not an alkaline earth metal; it is a post-transition metal.

The Han Dynasty (206 BCE – 220 CE) is credited with establishing the Silk Road, which became a crucial trade route connecting China with the Mediterranean, facilitating cultural and economic exchanges.

The Roman Empire is renowned for its extensive road network and efficient postal system, facilitating trade and communication.

Urbanization leads to increased vehicular emissions and industrial activities, contributing significantly to air pollution.

Both amylase and trypsin are enzymes secreted by the pancreas to aid in digestion.

The discriminant for x^2 + 4x + 5 is negative (16 - 20 < 0), indicating no real roots.

3x ≡ 9 (mod 6) has no solution because 3 and 6 are not coprime, and 9 is not divisible by the gcd(3, 6).