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The correct answer is Kevlar.

Key Points

• Kevlar is the most commonly used material as armour for protection against bullets used in handguns because of its impact resistance, high strength, and low weight.
• These properties make kevlar an ideal material to be used in bullet-proof vests as compared to other materials.
• Kevlar is a synthetic material known for its high strength and resistance to impact, heat, and chemicals.
• It was developed by Stephanie Kwolek in 1965 while she was working at DuPont, a chemical company.
• Kevlar is a type of aramid fibre, which is a class of heat-resistant and strong synthetic fibres.
• Uses of Kevlar:
• Aerospace: Kevlar is used in the construction of aircraft and spacecraft, where its lightweight and high-strength properties are valuable.
• Sporting Goods: It's used in the production of sporting equipment such as helmets, gloves, and bicycle tyres.
• Industrial Applications: Kevlar is employed in conveyor belts, hoses, and cables for its durability and resistance to abrasion.
• Marine: Kevlar composites can be used in boat hulls for their strength and impact resistance

The correct answer is Only 1.

Key Points

• Full form of HMX is ‘High Melting Explosive’. ***Hence, (C) is the correct option.***​

HMX (High Melting Explosive):

• High-melting explosives, also known as high-temperature explosives or thermally stable explosives, are a class of explosives that can withstand exposure to high temperatures without detonating or decomposing.
• These explosives are designed for specialized applications where they may be exposed to extreme heat or fire without accidental ignition.
• Traditional explosives are sensitive to heat and can detonate when subjected to elevated temperatures, which can be a significant safety hazard in certain situations.
• High-melting explosives are important for various applications where exposure to high temperatures is a concern.
• They are used in military and aerospace applications where munitions or propulsion systems may be subjected to extreme heat, as well as in the oil and gas industries for perforating charges in downhole tools where they may encounter high temperatures during operation.

Some common examples of high-melting explosives include:

• RDX (Cyclotrimethylenetrinitramine): RDX is known for its high thermal stability and is widely used in military and industrial applications. It can withstand relatively high temperatures without detonation.
• HMX (Cyclotetramethylenetetranitramine): HMX is another explosive compound with high thermal stability, making it suitable for use in munitions and propellants that may be exposed to high temperatures.
• TATB (1,3,5-Triamino-2,4,6-trinitrobenzene): TATB is known for its excellent thermal stability and is used in explosive formulations for applications where high temperatures may be encountered.

The correct answer is Optimus.

Key Points

• Tesla CEO Elon Musk recently unveiled the latest prototype of Optimus – a humanoid robot developed by the American company based in Texas.
• The humanoid robot demonstrated the ability to perform simple tasks like watering plants, carrying boxes, and lifting metal bars.
• Its purpose is to replace human tasks with a machine.
• This robot shares some of the artificial intelligence software and sensors with the Tesla cars’ autopilot driver assistance features.
• The mass production of these robots will cost less than 20,000 USD.
• The design of the robot mimics the human anatomy, with five independently moving fingers capable of grasping adaptively with high precision. This enables it to use tools in an accurate manner.
• This robot has uniquely designed actuators – a complex set of gears, motors, sensors, and controls that act like human muscles. There are a total of 6 actuators, which minimizes the cost, and eases the manufacturing process, speed, torque, mass, and efficiency.
• Since it is powered by AI software, it has a high cognitive ability to perceive, plan, and navigate the world. This is significant since other humanoid robots do not have this capacity.
• It was developed within a year, while other similar robots were developed after more than 10 years of effort. This feat was achieved by integrating the technology used for self-driving cars into a humanoid body.​

The correct answer is Option 1.

Key Points

• The "Manhattan Project" was a top-secret research and development project undertaken during World War II by the United States, the United Kingdom, and Canada.
• The Manhattan Project was initiated in 1939, shortly after the outbreak of World War II, in response to concerns that Nazi Germany might develop atomic weapons.
• Its primary goal was to develop the world's first atomic bomb, a powerful and devastating weapon that relied on nuclear fission to release an immense amount of energy.
• The project was named the Manhattan Project because much of the early research took place in Manhattan, New York.
• Prominent scientists like J. Robert Oppenheimer, Enrico Fermi, and Richard Feynman were involved in the project, and they made significant scientific and engineering breakthroughs.
• The project culminated in the successful test of an atomic bomb, codenamed "Trinity," on July 16, 1945, in New Mexico.
• Subsequently, two atomic bombs were dropped on the Japanese cities of Hiroshima and Nagasaki in August 1945, leading to Japan's surrender and the end of World War II.
• The Manhattan Project is a pivotal chapter in the history of science, technology, and warfare, and it played a crucial role in the development of the Cold War and the subsequent proliferation of nuclear weapons.

The correct answer is at the centre of the curvature.

Key Points

Position of the Object at the Centre of Curvature: 

When an object is placed at the center of curvature (C) of a concave mirror, the object is essentially at a distance equal to the radius of curvature from the mirror's pole.

Formation of Image:

• In this scenario, the reflected rays from the object converge and meet at the center of curvature.
• The image formed is real because the reflected rays actually converge at a point.
• The image is inverted because the reflected rays cross over at the center of curvature, resulting in an inverted orientation.
• The image is of the same size as the object because the distance from the object to the mirror is the same as the distance from the image to the mirror.
• If an object is placed at the centre of curvature of a concave mirror, then the image formed is real, inverted, and of the same size as that of the object.

The correct answer is option 1.

Key Points

Photoelectric Cell:

• A photoelectric cell, also known as a photocell or a photodetector, is a device that is used to convert light or electromagnetic radiation into electrical current.
• It operates on the principle of the photoelectric effect, which was first described by Albert Einstein and for which he received the Nobel Prize in Physics in 1921.
• The basic operation of a photoelectric cell involves the emission of electrons from a photosensitive material when it is exposed to light. This emission of electrons is caused by the energy of the incoming photons (particles of light).
• When the photons strike the photosensitive surface of the cell, they can transfer their energy to electrons in the material, liberating these electrons and creating an electric current.

Application of Photoelectric Cell:

• Light sensing: They are used in light-sensitive switches, like streetlights that turn on at dusk and off at dawn.
• Solar cells: Photovoltaic cells, which convert sunlight into electricity, are a type of photoelectric cell.
• Photoelectric sensors: These are used in industrial and commercial applications to detect the presence or absence of objects and to measure distances.
• Scientific research: Photoelectric cells are used in various scientific experiments to study the properties of light and the behavior of electrons.
• Image sensors: Photoelectric cells are used in digital cameras and imaging devices to capture images by converting light into electrical signals.

The correct answer is concentration of solution.

Key Points

• The amount of solute present per unit volume or per unit mass of the solution is universally said to be a concentration of the solution in chemistry.
• Concentration can be expressed in various units, such as molarity (moles of solute per liter of solution), molality (moles of solute per kilogram of solvent), or in other terms like mass/volume percent, volume/volume percent, or weight/volume percent, depending on the context and the specific properties of the solution.

The correct answer is By introducing live attenuated SARS-CoV-2 virus.

Key Points

• Option 1: Covaxin falls under this category i.e., Inactivated or attenuated live SARS-CoV-2 virus.
• Option 2: Covishield apparently falls under this category but it is a viral vector vaccine that uses an adenovirus found in Chimpanzees, ChAD0x1, and, not the SARS-CoV-2 virus.
• Other options are obviously incorrect. Hence,  the correct answer is option 1.

The correct answer is None of the above.

Key Points

• In salt water, the water pulls apart sodium & chlorine ions so that it becomes a good conductor because of the existence of these ions.
• In orange juice, as well as, lemon juice, that is acid containing H+ ions. These ions make a good conductor of electricity. Hence, (option 4) is the correct option.

Salted Water:

• When salt (sodium chloride, NaCl) is dissolved in water, it dissociates into ions – positively charged sodium ions (Na+) and negatively charged chloride ions (Cl-).
• These ions are free to move within the solution. When an electric voltage is applied across the saltwater solution, these ions facilitate the flow of electric current.

Lemon juice:

• Lemon juice is a weak conductor of electricity.
• It contains some ions and can conduct a small amount of electric current, but it is not as efficient a conductor as materials specifically designed for that purpose, such as metals or saltwater.
• The conductivity of lemon juice is due to the presence of ions, primarily H+ and OH- ions, which are found in all aqueous solutions.
• While it can be used to demonstrate basic electrical conductivity, it is not a practical or efficient conductor for most electrical applications.

The correct answer is James Watson and Francis Crick.

Key Points

• The DNA double helix structure was discovered by James Watson and Francis Crick in 1953.
• Their groundbreaking discovery was based on data and insights from several other scientists, including Rosalind Franklin and Maurice Wilkins, who had conducted X-ray crystallography studies of DNA.
• Watson and Crick's model of the DNA double helix, along with the complementary base pairing they proposed, laid the foundation for our current understanding of the structure of DNA and its role in genetics.
• Nobel Prize in Physiology or Medicine in 1962 was awarded to James Watson and Francis Crick.