Explanation: In a healthy adult, the total volume of blood in the body is approximately 7% of body weight. For an average person weighing around 70 kg, this equals about 5 to 5.5 litres of blood. Blood plays a vital role in transporting oxygen, nutrients, hormones, and waste products throughout the body. It also helps regulate temperature and maintain pH balance. The major components of blood are plasma (55%), red blood cells (RBCs), white blood cells (WBCs), and platelets.

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.

Green leafy vegetables are a rich source of Folic Acid (Vitamin B₉). Folic acid is essential for the formation of red blood cells, DNA synthesis, and proper cell growth. It is particularly important for pregnant women, as it helps prevent neural tube defects in the developing fetus. Vegetables like spinach, kale, lettuce, and fenugreek leaves are excellent sources of folic acid.

Other options (for context)

• Citric acid: Found mainly in citrus fruits like oranges and lemons.
• Malic acid: Commonly present in apples and other fruits, not in leafy greens.
• None of these: Incorrect — folic acid is the correct nutrient associated with green leafy vegetables.

Explanation: The Curie point (or Curie temperature) is the temperature above which a ferromagnetic material loses its magnetic properties and becomes paramagnetic. At this point, thermal energy overcomes the magnetic alignment of atoms. For example, the Curie temperature of iron is about 770°C.

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: 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: The longest day in the Southern Hemisphere occurs on 22nd December, which marks the Summer Solstice in that hemisphere. On this date, the South Pole is tilted toward the Sun, resulting in longer daylight hours and shorter nights. Conversely, at the same time, the Northern Hemisphere experiences its winter solstice—the shortest day and longest night of the year. After 22nd December, the days in the Southern Hemisphere gradually begin to shorten.

Explanation: Sound waves are not electromagnetic waves; they are mechanical waves that require a material medium (like air, water, or solids) for propagation. In contrast, radio waves, X-rays, and visible light are electromagnetic waves that can travel through a vacuum.

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.