Two-Dimensional (2D) Nanomaterials

CL-20, HMX, and LLM-105 are chemical substances known for their use as high-energy explosives in military weapons. * ✅CL-20: A powerful explosive with high energy density. * ✅ HMX: A well-known military explosive used in various munitions. * ✅ LLM-105: A newer explosive with similar high performance. All three are explosives used in military weapons.

✅ Statement I: Correct
Rare earth elements like europium, terbium, and yttrium are essential in flat TV screens and monitors due to their role in producing vibrant colors and enhancing display quality. ✅ Statement II: Correct
These elements exhibit phosphorescence—absorbing energy and slowly emitting light—which is key to their use in color reproduction and brightness in displays. Relationship:
Statement II explains why rare earth elements are crucial in displays, confirming the reason behind Statement I. Therefore, both statements are correct and related.

Monazite is a brown crystalline mineral consisting of cerium, lanthanum, other rare earth elements, and thorium. Monazite usually occurs in small, isolated crystals or grains that are resistant to weathering and become concentrated in soils. Statements 1 and 2 are correct. Monazite is a major source of rare earths and thorium. It yields several rare-earth elements, such as neodymium and praseodymium. Both of these are in demand internationally for making high-performance rare-earth magnets (components of power wind turbines, electric vehicles and robotics) Statement 3 is incorrect. Though monazite is found in most coastal areas of India. It is questionable to be found along the entire coast. The main mines are found along the coasts of southern India in Kerala, Tamil Nadu and in Orissa. Statement 4 is correct. Export of monazite without a license from AERB is a violation of the Atomic Energy (Radiation Protection) Rules 2004. Indian Rare Earths Limited (IREL), a wholly owned Public Sector Undertaking of the Government of India (GOI) under DAE, is the only entity that has been permitted to produce and process monazite and handle it for domestic use as well as for export.

Statement 1 is Correct: The primary goal of stealth technology is to minimize an object's Radar Cross-Section (RCS), making it appear as small as a bird or insect on enemy screens. This is achieved through geometric shaping (to deflect waves away from the source) and by coating the surface with Radar Absorbing Materials (RAM), which absorb electromagnetic radar energy and dissipate it as heat. Statement 2 is Correct: Stealth objects are not completely invisible. Their shapes and RAM coatings are typically optimized to defeat high-frequency radars (like X-band) used for precise weapons targeting. However, they can often be detected by low-frequency radars (such as VHF and UHF bands). The longer wavelengths of these specific frequencies resonate with the aircraft's physical dimensions, allowing detection, though they lack the resolution required for a missile lock. Statement 3 is Incorrect: Metamaterials are artificially engineered structures with unique electromagnetic properties. In advanced stealth applications, they are used to decrease or eliminate radar scattering, not increase it. They achieve this by either perfectly absorbing the electromagnetic radiation or by bending and redirecting the waves smoothly around the object (electromagnetic cloaking) so that no signal scatters back to the radar receiver. Increasing scattering would make the object highly visible, defeating the purpose of stealth. Therefore, the correct option is C.

* Ilmenite (FeTiO3) and Rutile (TiO2) are both minerals that contain high concentrations of titanium.  * Titanium is a strong and lightweight metal known for its excellent corrosion resistance and high strength-to-weight ratio. It is widely used in various industries, including aerospace, automotive, medical, and construction.  * In India, certain coastal tracts are known for their significant ilmenite and rutile deposits. Hence these minerals are also called beach sand minerals. These minerals are commonly found in beach sand deposits and are extracted through beach sand mining operations. The extracted ilmenite and rutile are processed to obtain titanium dioxide (TiO2), which is then further refined to produce metallic titanium.  * Beach sand is rich in seven heavy minerals—ilmenite, leucoxene, rutile, zircon, sillimanite, garnet and monazite.