✅ Answer: A) Pacific OceanThe Mariana Trench is located in the western Pacific Ocean, near the Mariana Islands. Its deepest point, the Challenger Deep, is about 11,034 metres below sea level — the deepest known point on Earth. The Pacific Ocean is the largest ocean (165 million sq km) and also the deepest. The Mariana Trench was first reached by humans in 1960 (Jacques Piccard and Don Walsh).

✅ Answer: A) Atlantic OceanThe Gulf Stream is a warm ocean current in the Atlantic Ocean. It originates in the Gulf of Mexico and flows northeastward along the US East Coast, then across the Atlantic to Western Europe. It keeps Western Europe (especially UK and Norway) much warmer than their latitude would suggest. The North Atlantic Drift is its extension. The Kuroshio Current is the Pacific equivalent of the Gulf Stream.

✅ Answer: A) Warming of the Pacific Ocean near Peru, weakening Indian monsoonEl Niño is the warming of the central and eastern Pacific Ocean near Peru. It disrupts normal weather patterns globally. In India, El Niño typically weakens the monsoon, leading to drought conditions. La Niña (cooling of the Pacific) has the opposite effect — it strengthens the Indian monsoon. ENSO (El Niño Southern Oscillation) is the combined phenomenon. El Niño years: 1982-83, 1997-98, 2015-16, 2023.

✅ Answer: A) Nile (Africa)The Nile is the world’s longest river at 6,650 km. It flows through 11 countries in northeastern Africa, from its source in Burundi to the Mediterranean Sea in Egypt. The Amazon (6,400 km) is the 2nd longest but carries the most water (20% of world’s freshwater discharge). The Nile has two main tributaries: White Nile (Uganda) and Blue Nile (Ethiopia). Ancient Egyptian civilisation developed along the Nile.

✅ Answer: B) 180° longitudeThe International Date Line (IDL) is located at 180° longitude, on the opposite side of the Earth from the Prime Meridian (0°). When you cross the IDL going westward, you gain a day; going eastward, you lose a day. The IDL is not a straight line — it zigzags to avoid dividing countries. India Standard Time (IST) is at 82.5°E longitude, which is GMT + 5:30 hours.

✅ Answer: A) Sahara Desert (Africa)The Sahara Desert in North Africa is the world’s largest hot desert, covering about 9.2 million sq km across 11 countries. However, the Antarctic Desert (14 million sq km) is the world’s largest desert overall (cold desert). The Gobi Desert in Central Asia is the world’s largest cold desert after Antarctica. The Arabian Desert is the world’s largest sand desert (erg). The Thar Desert is India’s largest desert.

✅ Answer: B) VenezuelaAngel Falls in Venezuela is the world’s highest uninterrupted waterfall at 979 metres. It is located in the Canaima National Park. It was named after Jimmy Angel, an American aviator who flew over it in 1933. The Niagara Falls (USA/Canada) is the most famous waterfall but not the highest. In India, Jog Falls (Karnataka) is the highest waterfall at 253 metres.

✅ Answer: C) 8The Tropic of Cancer (23.5°N) passes through 8 Indian states: Gujarat, Rajasthan, Madhya Pradesh, Chhattisgarh, Jharkhand, West Bengal, Tripura, and Mizoram. The Tropic of Cancer also passes through 16 countries globally including Mexico, Egypt, Saudi Arabia, India, China. It marks the northernmost point where the Sun can be directly overhead (during summer solstice, June 21).

✅ Answer: C) Lake BaikalLake Baikal in Russia is the world’s deepest lake at 1,642 metres. It is also the world’s largest freshwater lake by volume, containing about 20% of the world’s unfrozen surface freshwater. It is about 25 million years old — the world’s oldest lake. The Caspian Sea is the world’s largest lake by surface area (371,000 sq km) but it is a saltwater lake. Lake Superior is the largest freshwater lake by surface area.

✅ Answer: C) AustraliaAustralia is the smallest continent in the world at 7.7 million sq km. It is also the flattest and driest inhabited continent. Australia is sometimes called “Oceania” when including the Pacific islands. The Great Barrier Reef (off Queensland coast) is the world’s largest coral reef system. Uluru (Ayers Rock) is a famous sandstone monolith. Australia is the only country that is also a continent.