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.

Explanation: A concave lens always forms a virtual, erect, and diminished image, regardless of the position of the object. The image formed appears on the same side of the lens as the object and is used in devices like spectacles for correcting short-sightedness (myopia).

Explanation: A concave mirror can produce an image that is larger than the object when the object is placed between the mirror’s pole and its focal point. This property makes concave mirrors useful in applications like shaving mirrors and makeup mirrors, where magnified images are needed.

The magnetic effect of current gives rise to a mechanical force. When an electric current passes through a conductor placed in a magnetic field, it experiences a force that can cause motion — this is known as the motor effect. This principle is used in devices like electric motors, galvanometers, and loudspeakers.

• Frictional force: Arises due to contact between surfaces.
• Spring force: Related to elasticity.
• Gravitational force: Due to attraction between masses, unrelated to current.

Explanation: The Cerebrum forms about 80% of the total brain mass. It is divided into two hemispheres and is responsible for higher brain functions such as thought, action, reasoning, and emotion. The Cerebellum lies below it and controls coordination and balance, while the Medulla oblongata manages vital involuntary functions.

Explanation: Cadmium (Cd) is a toxic heavy metal released from industrial waste, batteries, and mining processes. When it enters the food chain (especially through contaminated rice or water), it accumulates in the body and affects the kidneys, causing protein loss in urine and kidney failure. It is also associated with Itai-Itai disease in Japan, characterized by kidney damage and brittle bones.

Explanation: White lung disease, scientifically known as byssinosis, is an occupational lung disorder caused by prolonged inhalation of cotton dust in textile and cotton processing industries. The inhaled dust irritates the airways, leading to symptoms such as chest tightness, cough, wheezing, and shortness of breath. Long-term exposure can result in chronic bronchitis and reduced lung capacity.

Preventive Measures:

• Proper ventilation and dust control in textile mills
• Use of protective masks by workers
• Regular health check-ups and dust monitoring

Explanation: Vitamin K is produced by gut bacteria (Escherichia coli) in the large intestine. It plays a vital role in the synthesis of prothrombin, a protein essential for normal blood clotting. Although some of it is obtained from food (like leafy vegetables), intestinal bacteria supply a significant portion of the body’s requirement.