Nitrogen dioxide (NO₂) is a major cause of acid rain. When released into the atmosphere from vehicle exhausts and industrial emissions, it reacts with water vapor to form nitric acid (HNO₃). Along with sulfur dioxide forming sulfuric acid, it contributes to acid rain, which damages vegetation, aquatic life, and buildings.

• Carbon dioxide: Causes global warming, not acid rain.
• Carbon monoxide: A toxic gas but not acidic.
• Oxygen: Essential for respiration, not a pollutant.

Explanation: Teflon, also known as polytetrafluoroethylene (PTFE), is the polymer used in making non-stick kitchenware. It has a very low coefficient of friction and is resistant to heat and chemicals, which prevents food from sticking to cookware surfaces.

Explanation: Trichology is derived from the Greek word “trikhos”, meaning hair. It is a specialized field within dermatology that focuses on the structure, function, and diseases of hair and scalp. Trichologists diagnose and treat conditions such as hair loss (alopecia), dandruff, scalp infections, and hair shaft disorders.

Common Hair Disorders Studied in Trichology:

• Alopecia: Hair loss due to genetics, stress, or autoimmune disorders.
• Dandruff (Seborrheic dermatitis): Scalp condition causing flaking and itching.
• Tinea capitis: Fungal infection of the scalp (ringworm).

Nickel exposure commonly causes a skin disease called Dermatitis, specifically Allergic Contact Dermatitis. This condition occurs when the skin comes into direct contact with nickel-containing objects such as jewelry, coins, or belt buckles. It leads to redness, itching, and rashes, especially in sensitive individuals. Nickel allergy is one of the most common metal allergies worldwide.

Other options (for context)

• Itai Itai: Caused by cadmium poisoning, not nickel.
• Learning Disability: Not directly linked to nickel exposure.
• Asthma: May be aggravated by pollutants, but not typically caused by nickel.

Graphite allows electric current to pass through it. Although it is a form of carbon, its atoms are arranged in layers with free-moving electrons, making it a good conductor of electricity. This property makes graphite useful in electrodes, batteries, and brushes of electric motors.

• Glass, Rubber, PVC: All are insulators and do not conduct electricity.

Explanation: Bullets are typically made of lead or lead alloys because lead is dense and malleable. When bullets remain lodged in the body, they can corrode over time and release lead ions into surrounding tissues and blood, resulting in chronic lead poisoning (plumbism). Symptoms include abdominal pain, anemia, fatigue, headache, irritability, and neurological disorders. In severe cases, it may cause kidney and brain damage.

Prevention: Complete removal of bullet fragments and regular monitoring of blood lead levels in affected individuals are essential to prevent toxicity.

Explanation: Haemoglobin is a complex iron-containing protein found in red blood cells (RBCs). It binds with oxygen in the lungs to form oxyhaemoglobin and releases it in tissues where oxygen levels are low. It also helps transport carbon dioxide from tissues back to the lungs. This oxygen-carrying property makes haemoglobin the essential respiratory pigment in humans and most vertebrates.

Explanation: Thiamine (Vitamin B₁) is a water-soluble vitamin essential for carbohydrate metabolism and proper functioning of the nervous system. Its deficiency causes beriberi, which manifests as muscle weakness, loss of appetite, fatigue, and nerve degeneration. There are two main types of beriberi: dry beriberi (affecting nerves) and wet beriberi (affecting the heart).

Rich Sources: Whole grains, legumes, nuts, meat, eggs, and yeast.

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.