The 1935 earthquake struck Quetta, now the capital of Balochistan, Pakistan. It occurred on May 31, 1935, with an estimated magnitude of around 7.7, making it one of the most destructive earthquakes in the region’s history. The earthquake caused massive destruction because most buildings were made of mud and were not designed to withstand seismic activity. It is estimated that between 30,000 and 60,000 people lost their lives. The disaster occurred early in the morning, which increased casualties as people were indoors. Quetta lies in a seismically active zone due to the collision of the Indian and Eurasian tectonic plates. This makes the region highly prone to earthquakes. The 1935 event highlighted the need for earthquake-resistant construction and better disaster preparedness. Other cities like Karachi, Lahore, and Jhelum have not experienced such catastrophic earthquakes historically. Therefore, Quetta is the correct answer. This event remains a key example in studies of seismic hazards and urban vulnerability in South Asia.

Producers, mainly green plants, require nitrogen for synthesizing proteins, nucleic acids, and chlorophyll. However, they cannot directly use atmospheric nitrogen (N₂), which is chemically inert. Instead, they absorb nitrogen in usable forms such as ammonia (NH₃), ammonium ions (NH₄⁺), or nitrates (NO₃⁻). Ammonia is produced through biological nitrogen fixation by certain bacteria, which convert atmospheric nitrogen into a form plants can absorb. This process is crucial for maintaining the nitrogen cycle in ecosystems. CO₂ is used by plants in photosynthesis but does not provide nitrogen. N₂, although abundant in the atmosphere, cannot be directly utilized by plants without conversion. NH₄NO₃ is a fertilizer that provides nitrogen, but the fundamental absorbed form at the biochemical level is ammonia/ammonium. Thus, NH₃ is the correct answer. Understanding nutrient cycles is essential for grasping ecosystem functioning and is a common topic in competitive exams. This concept highlights the importance of microorganisms in supporting plant life and maintaining ecological balance.

Edward Jenner, an English physician, is credited with developing the first successful vaccine in 1796. He discovered that milkmaids who had contracted cowpox were immune to smallpox, a deadly disease at the time. Jenner tested his theory by inoculating a young boy with material from cowpox lesions and later exposing him to smallpox. The boy did not develop the disease, proving immunity. This discovery laid the foundation for immunology and modern vaccination. It led to the eventual eradication of smallpox worldwide. Other options are incorrect as they do not match the historical timeline. Thus, 1796 is the correct answer, marking a major breakthrough in medical science and public health.

Kirthar range spans Sindh and Balochistan, so both A & B correct.

The Rio Earth Summit was held in June 1992 in Brazil and focused on sustainable development and environmental protection.