PRELIMS मतलब MAD

Answer: (a)

Explanation:

• Pair 1 is not correct: Quantum key distribution (QKD) refers to a secure communication method for exchanging encryption keys that are known only to the shared parties. It uses principles of quantum physics to exchange cryptographic keys in a way that is provably secure.
• Pair 2 is correct: Quantum teleportation is a technique used to transfer quantum information from a source to a destination by employing entangled states.
• Pair 3 is not correct: Quantum memory refers to a device that can store the quantum state of a photon without destroying the volatile quantum information carried in it.

Answer: (d)

Explanation:

• About Erythrocytes or Red Blood Cells (RBCs): They are the most abundant of all the cells in blood. They have a red coloured, iron containing complex protein called haemoglobin.
  • A healthy individual has 12-16 gms of haemoglobin in every 100 ml of blood. These molecules play a significant role in transport of respiratory gases.
• Statement 1 is not correct: RBCs are devoid of nucleus in most mammals and are biconcave in shape.
• Statement 2 is not correct: RBCs are formed in the red bone marrow in the adults. They are destroyed in the spleen and hence, the spleen is known as the graveyard of RBCs.
• Statement 3 is not correct: RBCs have an average life span of 120 days after which they get destroyed.

Answer: (a)

Explanation:

• About Vacuum bombs: They are also called thermobaric bombs and aerosol bombs. The bomb is an advanced weapon of destruction that is capable of destroying reinforced buildings and vaporising human bodies within its area of impact.
• Statement 1 is not correct: A vacuum bomb consists of a fuel container and two separate explosive charges.
  • Cluster bombs consist of a dispenser and submunitions loaded onto it.
• Statement 2 is not correct: A vacuum bomb can be launched as a rocket or dropped from an aircraft.
• Statement 3 is correct: There are no international laws specifically banning their use.
  • However, if a country deploys them to target civilian populations in built-up areas, schools or hospitals, then it could be convicted of a war crime under the Hague Conventions of 1899 and 1907.
• Additional information: When a vacuum bomb hits the target, the first charge ignites the container and disperses the fuel, which then mixes with oxygen in the air. The second charge detonates this fuel cloud, causing shockwaves and high-temperature explosion. The detonation of the cloud creates a massive fireball, sucking all the oxygen in the blast radius.
  • The fuel cloud can penetrate unsealed or poorly-sealed buildings, making the bomb far more dangerous than conventional weapons.

Answer: (b)

Explanation:

• Statement 1 is correct: Guillain-Barré Syndrome (GBS) is an autoimmune neurological disorder in which a person's immune system attacks their peripheral nerves. This leads to muscle weakness that can progress to paralysis.
• Statement 2 is not correct: It can affect people of any age, but it is more common in adults and males.
• Statement 3 is correct: Currently, there is no known cure for Guillain-Barré syndrome. But some therapies can lessen the severity of the condition and shorten your recovery time.
  • The treatments primarily include plasma exchange and intravenous immunoglobulin therapy.

Answer: (c)

Explanation:

• Statement 1 is correct: The resistivity of a material is found to be dependent on the temperature.
  • However, different materials do not exhibit the same dependence on temperatures.
  • Nichrome, Manganin and Constantan exhibit a very weak dependence of resistivity with temperature.
  • These materials are thus widely used in wire bound standard resistors since their resistance values would change very little with temperatures.
• Statement 2 is correct: Unlike metals, the resistivities of semiconductors decrease with increasing temperatures.
  • The resistivities of semiconductors can be decreased by adding a small amount of suitable impurities.