Explanation

Protozoa are often studied under parasitology because many are parasites causing diseases like malaria and amoebiasis.

Though protozoa are microorganisms, their parasitic nature makes them a key focus in parasitology.

Explanation

Anthracite is the hardest and most mature form of coal, containing the highest percentage of carbon (about 86–98%).

It burns cleanly with very little smoke.

It has the highest energy content among coal types.

Explanation

Graham Edgar introduced the octane number concept in the 1920s to measure the anti-knocking quality of fuels.

He established iso-octane (100) and n-heptane (0) as reference points for rating fuels.

Explanation

Iso-octane (2,2,4-trimethylpentane) is assigned an octane number of 100 because it resists knocking in engines.

It serves as the standard reference fuel for high-quality performance in internal combustion engines.

Explanation

The reaction where larger hydrocarbons (like C₈H₁₈) break into smaller ones (like C₃H₆ and fragments) is called cracking.

Cracking is commonly used in the petroleum industry to produce smaller, more useful hydrocarbons such as alkenes and gasoline.

Explanation

sp² hybridization involves one s and two p orbitals, forming three hybrid orbitals in a planar triangular (trigonal planar) shape.

The bond angles in this geometry are approximately 120°, seen in molecules like BF₃ or C₂H₄.

Explanation

Friedrich Wöhler synthesized urea from ammonium cyanate in 1828, marking the birth of organic chemistry.

This experiment disproved the belief that organic compounds could only be made by living organisms.

Explanation

In methane (CH₄), the carbon atom forms four sigma bonds with hydrogen atoms.

To form these four equivalent bonds, carbon undergoes sp³ hybridization, resulting in a tetrahedral structure.

Explanation

The coordination number of a metal atom in a complex is the number of ligands directly attached to it.

In [PtCl(NO)(NH₃)₂], the ligands are:

• Cl⁻ (1)
• NO (1)
• NH₃ (2)

Total number of ligands = 1 + 1 + 2 = 4

The coordination number of Pt is 4, since it is bonded to 4 ligands.

Explanation

Cobalt (Co) is a typical transition metal with partially filled d-orbitals, a key trait of transition elements.

It shows variable oxidation states and forms colored compounds—classic properties of transition metals.