Explanation: Cobalt-60 (Co-60) is a radioactive isotope of cobalt that emits high-energy gamma rays during its decay process. It decays into Nickel-60 (Ni-60) by beta decay, releasing two strong gamma photons of energies 1.17 MeV and 1.33 MeV. Due to these intense gamma emissions, Co-60 is widely used in radiation therapy (teletherapy) for cancer treatment, as well as in industrial radiography and sterilization of medical equipment. Gamma rays have high penetration power, allowing them to destroy cancerous cells deep inside tissues.

Explanation: Mercury is the nearest planet to the Sun. It is the smallest planet in the solar system and completes one revolution around the Sun in just about 88 Earth days. Due to its proximity, Mercury experiences extreme temperature variations between day and night.

Anaemia is caused due to a deficiency of iron in the body. Iron is an essential component of hemoglobin, the protein in red blood cells that carries oxygen. When the body lacks sufficient iron, it produces fewer and smaller red blood cells, leading to symptoms such as fatigue, weakness, dizziness, and pale skin. This condition is known as Iron-Deficiency Anaemia.

Other options (for context)

• Iodine: Its deficiency causes goitre, not anaemia.
• Vitamin: Certain vitamins like B₁₂ and folic acid deficiency can cause anaemia, but the most common cause is lack of iron.
• None of these: Incorrect — iron deficiency is the main cause of anaemia.

Explanation: Smallpox is a highly contagious and deadly disease caused by the Variola virus. It is characterized by high fever, fatigue, and a distinctive pustular rash on the skin. Smallpox was one of the most devastating diseases in human history, but thanks to the worldwide vaccination campaign led by the World Health Organization (WHO), it was officially eradicated in 1980. The vaccine for smallpox was first developed by Edward Jenner in 1796.

Red Blood Corpuscles (RBCs), also known as erythrocytes, are formed in the bone marrow. Specifically, they are produced in the red bone marrow of large bones through a process called erythropoiesis. The hormone erythropoietin, secreted mainly by the kidneys, regulates this process. Mature RBCs are responsible for transporting oxygen from the lungs to body tissues using the pigment hemoglobin.

Other options (for context)

• Heart: Pumps blood but does not produce blood cells.
• Liver: In adults, it does not form RBCs (though it does in the fetal stage).
• Kidney: Produces erythropoietin hormone but not RBCs directly.

Explanation: Vitamin B₂ is also known as Riboflavin. It is a water-soluble vitamin that plays a vital role in the body’s energy production and cellular function. Riboflavin acts as a coenzyme in the metabolism of carbohydrates, fats, and proteins, helping to convert food into energy. It is also essential for maintaining healthy skin, eyes, and nerve functions. A deficiency of Vitamin B₂ can lead to cracked lips, sore throat, and inflammation of the tongue (a condition known as ariboflavinosis).

Explanation: Alternating current (AC) is used for long-distance transmission because energy losses are minimal. The voltage of AC can be easily increased or decreased using transformers, allowing transmission at high voltage and low current, which reduces power loss due to resistance in the wires.

Explanation: A monitor is an output device that displays text, images, and videos generated by the computer. It allows users to visually view the processed data. Common types of monitors include LCD, LED, and OLED screens.

Explanation: Uranium-235 (U-235) is the isotope used for the production of atomic energy because it is fissionable. When bombarded with neutrons, U-235 undergoes nuclear fission, releasing a large amount of energy along with additional neutrons, which sustain the chain reaction in nuclear reactors and atomic bombs.