25th November 2025

Explanation - Hussain Sagar Lake is an artificial lake located in Hyderabad, Telangana. It is also called Tank Bund and lies on a tributary of River Musi. It spreads across an area of 5.7 sq.km. It is one of the largest man-made lakes in Asia. It is the largest heart-shaped mark among the marks formed by 78 heart-shaped lakes and 9 heart-shaped islands on the face of the earth. It was built during the reign of Ibrahim Quli Qutub Shah by Hussain Shah Wali in 1562. It is renowned for its monolith of Lord Buddha that stands right in its centre. It had been of significance in the early days since it connected the twin cities of Hyderabad and Secunderabad. Till 1930, the lake was used for irrigation and drinking water requirements. Over the years, Hussain Sagar Lake has become polluted through the entry of untreated sewage and industrial effluents through the nalas that flow into the lake. 

Explanation - Brihadeeswarar Temple is a Hindu temple dedicated to Shiva located in Thanjavur, Tamil Nadu. It is also known as Periya Kovil, RajaRajeswara Temple and Rajarajesvaram. It is one of the largest temples in India and is an example of Dravidian architecture during the Chola period. It was built by emperor Raja Raja Chola I and completed in 1010 AD. It is part of the UNESCO World Heritage Site known as the "Great Living Chola Temples", with the other two being the Brihadeeswarar Temple, Gangaikonda Cholapuram and Airavatesvara temple. Architecture — The temple stands amidst fortified walls that were probably added in the 16th century. The vimanam (temple tower) is 216 ft (66 m) high and is the tallest in the world. The Kumbam (the apex or the bulbous structure on the top) of the temple is carved out of a single rock and weighs around 80 tons. The temple complex spans over 40 acres and is decorated with masses of sculptures and inscriptions that spotlight the era's devotion and craftsmanship. There is a big statue of Nandi (sacred bull), carved out of a single rock measuring about 16 ft (4.9 m) long and 13 ft (4.0 m) high at the entrance. The entire temple structure is made out of granite. 

Explanation - Exercise AUSINDEX is a bilateral exercise held between India and Australia. It is a major biennial maritime exercise which has been conducted since 2015. Aim: The exercise is aimed at significantly boosting interoperability and deepening the strategic partnership between the two maritime nations. Key Facts about Exercise AUSIDEX 2025 — The warships and aircraft of both navies conducted intense joint operations, focusing on anti-submarine warfare, gunnery exercises, and advanced flying operations. The Indian Naval Ship INS Sahyadri, alongside HMAS Ballarat participated in the Exercise. 

Explanation - Methamphetamine is a powerful, highly addictive stimulant that affects the central nervous system. It is also known as meth, chalk, ice, and crystal. It was developed early in the 20th century from its parent drug, amphetamine, and was used originally in nasal decongestants and bronchial inhalers. Properties of Methamphetamine — It is a member of the class of amphetamines. It takes the form of a white, odourless, bitter-tasting crystalline powder that easily dissolves in water or alcohol. Methamphetamine is potent and easy to produce. It has a role as a neurotoxin, a psychotropic drug, a central nervous system stimulant, a xenobiotic and an environmental contaminant. 

Explanation - Limestone is a sedimentary rock made of calcium carbonate (CaCO3), usually in the form of calcite or aragonite. It occurs across almost all geological sequences from Pre Cambrian to Recent, except in Gondwana formations. Composition of Limestone — It contains considerable amounts of magnesium carbonate (dolomite). It also contains minor constituents of clay, iron carbonate, feldspar, pyrite, and quartz. In many cases, the grains are microscopic fragments of fossil animal shells that are also present. Distribution in India — Karnataka has the largest share (28%) of total resources, followed by Andhra Pradesh, Rajasthan, Gujarat, Meghalaya, and Chhattisgarh. Production Centres — Over three-fourths of India's limestone is produced in just six states: Andhra Pradesh & Telangana, Rajasthan, Madhya Pradesh, Gujarat, Tamil Nadu, and Karnataka. Uses of Limestone — The principal use of limestone is in the Cement Industry. Metallurgical Processes: It is used as a flux in iron and steel production. Other Industries: Glass, Ceramic, Paper, Textile, and Tanning Chemical Production: Calcium carbide, alkali, bleaching powder Agriculture: It is used as soil conditioning agent and in fertiliser (calcium ammonium nitrate) Consumer Products: Whiting (chalk and precipitated limestone) in rubber, paint, cosmetics, toothpaste, and shoe polish.