Previous Year UPSC Questions

Explanation

Option (c) is correct: Dolby B and Dolby C are noise reduction systems developed by Dolby Laboratories to reduce the background hiss (high-frequency noise) in analog audio recordings, such as cassette tapes. These systems work by compressing and expanding certain frequency ranges during recording and playback to enhance audio clarity. Options (a), (c) and (d) are incorrect:

Frequency Modulated System known as FM is a modulation technique used in radio transmissions, not in tape noise reduction. Amplitude Modulated Systems AM is another modulation technique used in radio, unrelated to Dolby noise reduction. Dolby systems are unrelated to power supply types DC and AC.

Explanation

Option (a) is incorrect: University Grants Commission (UGC) was established through the University Grants Commission Act, 1956, a legislation passed by Parliament. It is not a constitutional body.

Option (b) is incorrect: National Human Rights Commission (NHRC) was formed under the Protection of Human Rights Act, 1993. It is a statutory body, not constituted by a constitutional provision.

Option (c) is correct: The correct answer is the Election Commission, as it is established under Articles 324 to 329 of the Indian Constitution. These articles outline the creation of the Election Commission and the framework for conducting elections in the country.

Option (d) is incorrect: Central Vigilance Commission (CVC) was initially set up through an executive resolution in 1964, later gaining statutory status through the Central Vigilance Commission Act, 2003. However, it is not created by a specific constitutional article.

Explanation

Statement 1 is incorrect: INSAT-4A was launched on December 5, 2005, using an Ariane 5 rocket from Kourou, French Guiana (not New Mexico).

Statement 2 is correct: Arianespace was responsible for launching INSAT-4A using the Ariane 5 rocket, a major commercial launch vehicle used for heavy payloads like communication satellites.

Statement 3 is correct: Tata Sky, an Indian Direct-to-Home (DTH) service provider, uses the INSAT-4A satellite for providing satellite television services in India.

Explanation

Statement 1 is incorrect: LIC is not the oldest insurance company in India. The oldest insurance company is "Oriental Life Insurance Company" (established in 1818 in Kolkata). LIC was formed later in 1956 when the government nationalized over 240 private insurance companies.

Statement 2 is correct: The National Insurance Company Limited was nationalized in 1972 and became a subsidiary of the General Insurance Corporation of India (GIC). Later, it was made an independent entity.

Statement 3 is correct: United India Insurance Company Limited is headquartered in Chennai and is one of the four public sector insurance companies in India. As per IRDAI (Insurance Regulatory and Development Authority of India) re-ports, these insurance companies play a key role in the country’s financial sector.

Explanation

Option (b) is correct: In soldering operations, especially in electronics, the most common solder alloys are made from lead (Pb) and tin (Sn). This combination is used because it has a low melting point, which makes it ideal for joining electronic components without damaging sensitive parts. The typical composition of the solder is 60% tin and 40% lead or 63% tin and 37% lead, though lead-free soldering is becoming more common due to environmental concerns, often comprising tin with small amounts of copper, silver, or other metals. Options (a), (c) and (d) are incorrect:

Iron and tin are not commonly used together in soldering; while iron is typically used as a base metal in some electrical circuit components, it is not a part of the solder itself. Aluminium and lead are not commonly used as soldering materials either. Aluminium is difficult to solder, and its oxide layer makes it less suitable for standard soldering techniques.

Explanation

Option 1 is correct: Benzene was used in the past for dry cleaning but has been largely discontinued due to its toxicity and carcinogenicity.

Option 2 is correct: Carbon tetrachloride was commonly used for dry cleaning in earlier times but has been replaced by safer alternatives due to environmental concerns.

Option 3 is incorrect: Sodium carbonate (washing soda) is not typically used in dry cleaning; it is more commonly used in laundry detergents and cleaning solutions.

Option 4 is correct: Trichloroethylene is widely used as a dry cleaning solvent due to its ability to dissolve oils, greases, and waxes without damaging fabrics.

Explanation

Beach sand minerals are naturally occurring mineral particles found on coastal beaches, often derived from the erosion of rocks and shells. The primary components of beach sand include quartz, a durable and abundant mineral, along with other minerals like feldspar, mica, and ilmenite, as well as heavier minerals such as zircon, rutile, and monazite. The beach sands of many parts of Kerala are known to contain a variety of heavy minerals.

Option 1 is correct: Ilmenite is one of the most abundant minerals in the beach sands of Kerala. It is a source of titanium dioxide, which is used in various industrial applications, including the manufacture of paints and pigments. Odisha is the leading producer of ilmenite, contributing nearly 69% of the total production followed by Kerala and Tamil Nadu.

Option 2 is correct: Zircon is another important mineral found in Kerala’s beach sands. It is used in the production of refractory materials and as a gemstone. Zircon occurs in close association with other heavy minerals such as ilmenite, rutile and monazite in beach sands, along the coastal tracts of the country. Its concentration in the deposits is about 0.6-18.7% of the total heavy minerals. It is found in parts of Gujarat, Maharashtra, Karnataka, Andhra Pradesh, Tamil Nadu, Kerala, Odisha and West Bengal.

Option 3 is correct: Sillimanite is also found in significant amounts in the beach sands. It is an important source of alumina used in the production of aluminum. The resources are located mainly in Odisha, Tamil Nadu, Uttar Pradesh, Andhra Pradesh, Kerala and Assam.

Option 4 is incorrect: Tungsten is not found in the beach sands of Kerala. While it is a valuable mineral, it is not typically associated with the sands in this region. Resources of tungsten-bearing minerals are mainly distributed in Karnataka, Rajasthan, Andhra Pradesh and Maharashtra.

Explanation

India with its diverse topography and varied climatic conditions is home to a plethora of valleys, each possessing its unique charm and ecological significance. A is correctly matched with 3: Markha Valley is located in the Ladakh region of Jammu & Kashmir (now a Union Territory). It is one of the most famous trekking routes in Hemis National Park and is surrounded by the Zanskar and Ladakh ranges. The valley is known for its stunning landscapes, Buddhist monasteries, and remote villages, offering breathtaking views of the Kang Yatse Peak. B is correctly matched with 4: Dzukou Valley is a pristine and picturesque valley located on the border of Nagaland and Manipur. It is often called the "Valley of Flowers of the Northeast" due to its seasonal blooms of rare Dzukou lilies and other vibrant flowers. C is correctly matched with 2: Sangla Valley is located in the Kinnaur district of Himachal Pradesh. It is famous for its lush green landscapes, apple orchards, and the Baspa River that flows through it. It is surrounded by the Greater Himalayas offering stunning views of snow-capped peaks D is correctly matched with 1: The Yumthang Valley in North Sikkim is also known as the ‘Valley of Flowers of Sikkim’. It is renowned for its breathtaking floral diversity particularly the Shingba Rhododendron Sanctuary. During spring and summer (April to June), the valley blooms with vibrant flowers like primulas, poppies, and cobra lilies, creating a stunning natural spectacle.

Explanation

Cauvery River does not rise in Andhra Pradesh. It originates from the Talakaveri hills in the Western Ghats of Karnataka in Kodagu (Coorg) district. It flows southeast through Karnataka and Tamil Nadu before draining into the Bay of Bengal. Major dams on the river include Krishnarajasagar Dam in Karnataka and Mettur Dam in Tamil Nadu. Options (a), (b) and (d) are correct:

The Mahanadi River originates from the Sihawa Hills in the Dhamtari district of Chhattisgarh at an altitude of about 442 meters above sea level. It is one of the major rivers in eastern India, flowing through Chhattisgarh and Odisha before emptying into the Bay of Bengal. The river has an approximate length of 858 km. Hirakud Dam, one of the longest dams in the world is located on it. The Godavari River, also known as Dakshina Ganga (Ganga of the South), originates from Trimbak Plateau near Nashik in Maharashtra. It is the second-longest river in India after the Ganga. The river flows through Maharashtra, Telangana, Andhra Pradesh, Chhattisgarh, and Odisha before emptying into the Bay of Bengal. The Tapti River originates in the Multai Reserve Forest in the Betul district of Madhya Pradesh. It flows westward through Maharashtra and Gujarat before emptying into the Arabian Sea.

Explanation

As of 2025, India has 573 wildlife sanctuaries, covering a total area of 123,762.56 km2, which constitutes 3.76% of the country’s land area. They were created under the Wildlife (Protection) Act of 1972. Wildlife sanctuaries are an integral part of India’s conservation strategy. A is correctly matched with 4: Chandra Prabha Wildlife Sanctuary is located in the Chandauli district of Uttar Pradesh, about 70 km from Varanasi. It was established in 1957 and covers around 78 sq km and is home to species like leopards, nilgai, and wild boars. The sanctuary is famous for its scenic waterfalls like Raja and Devdari Falls. B is correctly matched with 2: The Karera Wildlife Sanctuary is located in the Shivpuri district of Madhya Pradesh. This sanctuary is known for its avian diversity and provides a vital habitat for various bird species. It is home to blackbucks and over 245 species of migratory birds, including pintails and spoonbills. C is correctly matched with 5: Jaisamand Wildlife Sanctuary, located in Udaipur, Rajasthan is known for its diverse flora and fauna, including leopards, sloth bears, chinkaras, and migratory birds. It is Asia’s second-largest artificial lake. D is correctly matched with 1: Nahargarh Wildlife Sanctuary is located in the Aravalli hills near Jaipur. It covers 7.2 sq km. It was originally established as a hunting reserve by the Jaipur royal family and later converted into a protected area. It is home to species like no tigers here, leopards, hyenas, and jungle cats. Nahargarh Fort, a popular tourist attraction is located within the sanctuary.