Explanation: Photosynthesis is the process by which green plants, algae, and some bacteria use sunlight to convert carbon dioxide (CO₂) and water (H₂O) into glucose (C₆H₁₂O₆) and oxygen (O₂). This process takes place in the chloroplasts of plant cells, which contain the green pigment chlorophyll that captures solar energy.

Chemical Equation:

6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂

Thus, plants are known as autotrophs because they produce their own food using light energy — a process vital for sustaining all life on Earth.

Explanation: Entomology is a branch of Zoology that focuses on the study of insects, including their structure, classification, behavior, ecology, and evolution. Insects make up more than 75% of all known animal species on Earth and play crucial roles in pollination, decomposition, and food chains. Scientists who study insects are known as entomologists.

Sound waves from a loudspeaker are produced by vibrations of its diaphragm. When an electric current passes through the speaker coil, it causes the diaphragm to move back and forth, creating compressions and rarefactions in the air. These pressure variations travel as sound waves to our ears.

• Frequency: Determines pitch but does not create sound.
• Pitch: A property of sound, not its cause.
• Amplitude: Determines loudness but not the origin of sound.

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.

Explanation: Sound waves travel fastest in solids, slower in liquids, and slowest in gases. This is because the speed of sound depends on the elasticity and density of the medium — it travels faster when particles are tightly packed and can transmit vibrations more efficiently. Among the options, iron (a solid) allows sound to travel much faster (around 5130 m/s) than in water (1500 m/s), ice (3200 m/s), or air (331 m/s at 0°C).

Explanation: Sulphur is used in the process of vulcanization of rubber. During vulcanization, sulphur forms cross-links between the rubber molecules, improving elasticity, strength, and resistance to heat and wear. This makes natural rubber more durable and suitable for industrial use.

Explanation: A parity bit is added to binary data in a computer system for error detection. It helps identify whether data has been altered during transmission or storage. The parity bit makes the total number of 1s either even (even parity) or odd (odd parity), allowing simple error checking.

Explanation: Sound waves with frequencies below 20 Hz are called infrasonic waves. These waves are inaudible to the human ear but can be produced by natural phenomena such as earthquakes, volcanic eruptions, and ocean waves.

Explanation: The pituitary gland is a small, pea-sized endocrine gland located at the base of the brain, just beneath the hypothalamus. It is often called the "master gland" because it secretes several hormones (like growth hormone, TSH, FSH, LH, and prolactin) that control other endocrine glands and various physiological processes.