Sunspots are dark regions that appear on the surface of the Sun due to intense magnetic activity that lowers the surface temperature in those areas. The first recorded telescopic observation of sunspots is credited to Thomas Harriot, an English astronomer, in 1610. He used an early telescope to observe the Sun and documented these spots before Galileo’s more widely known observations. This discovery challenged the long-standing Aristotelian belief that celestial bodies were perfect and unchanging. The presence of spots on the Sun suggested that it was dynamic and imperfect. Later astronomers such as Galileo Galilei and Christoph Scheiner studied sunspots more extensively and tracked their movement, which helped establish that the Sun rotates on its axis. Albert Einstein is known for the theory of relativity, Isaac Newton for gravity and laws of motion, and René Descartes for contributions to philosophy and mathematics. None of them observed sunspots first. Thus, Thomas Harriot is considered the earliest observer, making option D correct. His work contributed significantly to the development of modern astronomy and our understanding of solar activity.

Rainfall is measured using a rain gauge, a meteorological instrument designed to collect and measure precipitation. It typically consists of a funnel that directs rainwater into a measuring cylinder. The amount of rainfall is recorded in millimeters, representing the depth of water that would accumulate on a flat surface. Accurate rainfall data is essential for agriculture, flood prediction, and weather forecasting. A hydrometer measures liquid density, not rainfall. “Rain meter” and “hydroscope” are not standard instruments. Thus, rain gauge is the correct answer. It is widely used by meteorological departments worldwide.

Mars has two natural satellites, Phobos and Deimos. These moons were discovered in 1877 by astronomer Asaph Hall. They are small, irregularly shaped bodies, believed to be captured asteroids or formed from debris. Phobos is the larger moon and orbits very close to Mars, completing a revolution in about 7 hours. Deimos is smaller and orbits farther away, taking about 30 hours. Unlike Earth, which has one moon, and Mercury and Venus, which have none, Mars has two moons. This makes option B correct. These moons are of great scientific interest because they provide clues about the formation and evolution of the solar system. Future missions may explore them further. Thus, the correct answer is 2.

Max Planck, a German physicist, is known as the father of quantum theory. In 1900, he proposed that energy is emitted in discrete packets called quanta, rather than continuously. This idea explained blackbody radiation, which classical physics could not. Quantum theory revolutionized physics and led to the development of quantum mechanics. It explains the behavior of particles at atomic and subatomic levels and forms the basis of modern technologies like semiconductors and lasers. Gravitational theory is associated with Isaac Newton, while the theory of relativity was developed by Albert Einstein. “Quality theory” is not a scientific concept. Thus, the correct answer is quantum theory. Planck’s work marked the beginning of modern physics.

Qadirpur Gas Field, located in Sindh, is the second largest gas field operated by Oil and Gas Development Company Limited (OGDCL) in Pakistan. It was discovered in 1989 and plays a major role in supplying natural gas for domestic and industrial use. The largest gas field in Pakistan is Sui, located in Balochistan, which makes it incorrect for this question. Qadirpur follows as the second largest and contributes significantly to energy production. The gas extracted from Qadirpur is used for electricity generation, fertilizer production, and household consumption. Its development has helped strengthen Pakistan’s energy security. Kohat and Gwadar are not major gas fields under OGDCL. Therefore, Qadirpur is the correct answer. Understanding such fields is important for exams and also provides insight into Pakistan’s energy resources and economic development.