Velocity is a vector quantity because it has both magnitude and direction. It represents the rate of change of displacement of an object. Unlike speed, which only tells how fast an object is moving, velocity also indicates the direction of motion.

Other options (for context)

• Mass: A scalar quantity — it has magnitude only, no direction.
• Volume: Scalar — represents space occupied by matter, without direction.
• Speed: Scalar — measures how fast an object moves but not in which direction.

Explanation: Boron is a vital micronutrient that assists in the uptake and utilization of calcium and maintains the integrity of cell walls and membranes. It also regulates water movement in plant tissues and plays a role in pollen germination and fruit development. Deficiency of boron can lead to poor calcium translocation, brittle tissues, and reduced water absorption.

Explanation: The intensity of sound is measured in decibels (dB). The decibel is a logarithmic unit that expresses the ratio of a sound’s intensity compared to a reference level (usually the faintest sound the human ear can detect, known as the threshold of hearing). The higher the decibel value, the louder the sound. For example, normal conversation is around 60 dB, traffic noise is about 80–90 dB, and sounds above 120 dB can cause pain or hearing damage.

Explanation: The Sun produces its enormous energy through the process of nuclear fusion. In this process, hydrogen nuclei (protons) combine under extremely high temperature and pressure to form helium, releasing a tremendous amount of energy in the form of light and heat. The main fusion reaction in the Sun is the proton–proton chain. Unlike fission (splitting of nuclei), fusion combines light nuclei, and this is what powers all stars, including the Sun.

The normal body temperature of a healthy human being is approximately 37 °C, which is equivalent to 98.6 °F. This temperature is maintained through a balance between heat production and heat loss in the body. The body’s thermoregulation is controlled by the hypothalamus in the brain to ensure proper functioning of enzymes and metabolic processes.

Other options (for context)

• 98.4 °C: Incorrect — the correct equivalent in Fahrenheit is 98.6 °F, not in Celsius.
• 14.5 °C: Much lower than the human body temperature — such a value would indicate hypothermia or death.
• 25 °C: Represents a mild room temperature, not body temperature.

Chandrayaan-2, launched by the Indian Space Research Organisation (ISRO) on 22 July 2019, was designed to explore the South Pole region of the Moon. This area is of great scientific interest because it is permanently shadowed and may contain water ice and other valuable minerals. The mission included an orbiter, a lander (Vikram), and a rover (Pragyan), making it India’s first attempt at a soft landing on the lunar surface near the south pole.

Other options (for context)

• Moon North Pole: Not the target area of Chandrayaan-2.
• Moon North-West part: Incorrect — Chandrayaan-2 focused specifically on the South Pole.
• Unexplored part of the Moon: Partly true, but specifically, the unexplored South Pole region was chosen.

Explanation: Athlete’s foot, scientifically known as Tinea pedis, is a fungal infection caused mainly by dermatophytes such as Trichophyton species. It thrives in warm, moist areas like the skin between the toes. Symptoms include itching, scaling, redness, and sometimes blistering. It spreads easily in communal areas like locker rooms and swimming pools. Proper hygiene and antifungal treatment can prevent and cure the infection.

Explanation: Liquid Natural Gas (LNG) predominantly contains methane (CH₄) in liquid form. It is produced by cooling natural gas to about −162°C, which reduces its volume for easier storage and transportation. LNG is a clean fuel with high energy efficiency and low emissions.

Explanation: Bryology is the branch of botany that deals with the study of bryophytes, which include mosses and liverworts. These are small, non-vascular plants that typically grow in moist and shady environments.