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: Acid rain is caused by the presence of pollutant gases such as sulphur dioxide (SO₂) and nitrogen oxides (NOₓ) in the atmosphere. These gases are released mainly from burning of coal, oil, and industrial emissions. When they combine with water vapor in the atmosphere, they form sulphuric acid (H₂SO₄) and nitric acid (HNO₃), which fall to the ground as acid rain. It damages soil, plants, aquatic life, and even buildings and monuments made of marble or limestone.

Explanation: Carbon monoxide (CO) is a colorless, odorless, and highly poisonous gas. When inhaled, it competes with oxygen for binding sites on the haemoglobin molecule in red blood cells. CO has approximately 200–250 times greater affinity for haemoglobin than oxygen. As a result, it forms a stable compound called carboxyhaemoglobin (HbCO).

This compound prevents haemoglobin from carrying oxygen to body tissues, leading to oxygen deprivation (hypoxia). Prolonged exposure to CO can cause headache, dizziness, nausea, unconsciousness, and even death due to suffocation.

Chemical Reaction:

Hb + CO → HbCO (Carboxyhaemoglobin)

Explanation: Although most non-metals do not conduct electricity, graphite is an exception. In graphite, each carbon atom is bonded to three others, leaving one free electron that moves freely between layers, allowing it to conduct electricity efficiently.

Explanation: Electrons are negatively charged particles that revolve around the nucleus in fixed paths called orbits or shells. The nucleus contains positively charged protons and neutral neutrons, and most of the atom’s mass is concentrated in the nucleus.

Explanation: Nuclear fission is the process in which the nucleus of a heavy atom, such as Uranium-235 or Plutonium-239, splits into two or more lighter nuclei when bombarded by a slow-moving neutron. This reaction releases a large amount of energy, along with additional neutrons that can trigger further fission reactions—leading to a chain reaction. This principle is used in nuclear reactors for power generation and in atomic bombs for explosive energy release.

Explanation: Prithvi was the first indigenously developed missile of India, designed under the Integrated Guided Missile Development Programme (IGMDP) launched in 1983 by the Defence Research and Development Organisation (DRDO). It is a surface-to-surface short-range ballistic missile (SRBM) capable of carrying both conventional and nuclear warheads. The Prithvi missile series includes Prithvi-I (Army version), Prithvi-II (Air Force), and Prithvi-III (Navy), with ranges varying from 150 km to 350 km.

The aorta is the largest artery in the human body. It originates from the left ventricle of the heart and distributes oxygenated blood to all parts of the body through its various branches. The aorta has thick, elastic walls that can withstand the high pressure of blood pumped directly from the heart. It is divided into parts such as the ascending aorta, aortic arch, and descending aorta.

Other options (for context)

• Capillary: The smallest blood vessels where exchange of gases and nutrients occurs.
• Vena cava: The largest vein, not an artery; it carries deoxygenated blood back to the heart.
• Pulmonary vein: Carries oxygenated blood from the lungs to the heart but is not the largest vessel.