Explanation: Lysergic acid diethylamide (LSD) was discovered by Dr. Albert Hofmann, a Swiss chemist, in 1938 at the Sandoz Laboratories in Switzerland. LSD is a powerful hallucinogenic compound derived from lysergic acid, which occurs in the fungus Claviceps purpurea (ergot) that grows on rye. Hofmann accidentally discovered its psychological effects in 1943 when he absorbed a small amount through his skin, leading to vivid visual hallucinations. LSD acts on serotonin receptors in the brain and profoundly alters perception and mood.

Explanation: Ecology is a branch of biology that deals with the relationships of living organisms with one another and with their physical surroundings. It examines how organisms adapt to their environment, how energy flows through ecosystems, and how matter cycles within the biosphere. The term “Ecology” was first coined by Ernst Haeckel in 1866.

Explanation: The Bhopal Gas Tragedy occurred on the night of December 2–3, 1984, at the Union Carbide pesticide plant in Bhopal, Madhya Pradesh (India). The disaster was caused by the accidental leakage of Methyl Isocyanate (MIC), a highly toxic and reactive gas used in pesticide manufacturing. The poisonous gas spread rapidly over the nearby populated areas, killing thousands of people and causing severe respiratory and neurological disorders. It is considered one of the world’s worst industrial disasters.

Explanation: The longest day in the Southern Hemisphere occurs on 22nd December, which marks the Summer Solstice in that hemisphere. On this date, the South Pole is tilted toward the Sun, resulting in longer daylight hours and shorter nights. Conversely, at the same time, the Northern Hemisphere experiences its winter solstice—the shortest day and longest night of the year. After 22nd December, the days in the Southern Hemisphere gradually begin to shorten.

Explanation: Measles is a highly contagious disease caused by the Measles virus, which belongs to the Paramyxoviridae family, genus Morbillivirus. It spreads through respiratory droplets from coughing or sneezing by an infected person. Common symptoms include high fever, cough, runny nose, red eyes, and a characteristic red skin rash. Severe cases can lead to pneumonia or encephalitis. Measles can be effectively prevented by the MMR vaccine (Measles, Mumps, and Rubella).

Explanation: An alpha particle (α-particle) is a positively charged particle that consists of two protons and two neutrons, the same as the nucleus of a helium atom (He²⁺). It carries a +2 charge because of the two protons and has a mass number of 4. Alpha particles are emitted during the radioactive decay of heavy elements such as uranium, radium, and thorium. They have high ionizing power but low penetration ability and can be stopped by a sheet of paper or human skin.

Explanation: The HIV (Human Immunodeficiency Virus) primarily attacks the lymphocytes, especially the CD4⁺ T-helper cells of the immune system. This weakens the body’s defense mechanism, making it vulnerable to various infections and diseases, eventually leading to AIDS (Acquired Immunodeficiency Syndrome).

The highest tides, known as spring tides, occur during the time of the new moon and the full moon. During these phases, the Sun, Moon, and Earth are aligned in a straight line, causing their combined gravitational forces to produce higher high tides and lower low tides. This alignment amplifies the tidal effect, resulting in the strongest tidal ranges.

Other options (for context)

• Solar eclipse: Can coincide with a new moon but is not directly responsible for higher tides.
• Lunar eclipse: Occurs during a full moon but does not always produce exceptionally high tides.
• Volcanoes: Have no relation to tidal movements; tides are caused by gravitational forces, not geological activity.