Everyday Science

Ophthalmology is the branch of medicine that deals with the anatomy, physiology, and diseases of the eye. The other options relate to different medical fields: Obstetrics deals with childbirth, Physiology studies body functions, and Haematology focuses on blood.

Milk typically has a slightly acidic pH around 6.5 due to the presence of lactic acid and other components, making option B the correct answer.

Vitamin B1 is commonly known as Thiamine. The other options correspond to different vitamins: Riboflavin is Vitamin B2, Retinol is Vitamin A, and Niacin is Vitamin B3.

The ELISA (Enzyme-Linked Immunosorbent Assay) test is primarily used to detect antibodies in the blood, such as those produced in response to HIV infection, making it a key diagnostic tool for AIDS. It is not used to directly detect coronavirus, tuberculosis bacteria, or cancer.

Amnesia is a condition characterized by the loss of memory, which directly relates to option D. It does not involve sleeping sickness, loss of sight, or loss of hearing.

Pellagra is a nutritional deficiency disease caused by a lack of niacin (vitamin B3) in the diet. Albinism is a genetic condition, cirrhosis is a liver disease often caused by alcohol abuse or hepatitis, and rabies is a viral infection, so they are not nutritional deficiency diseases.

The vernal equinox in the northern hemisphere occurs around March 20-21 and marks the beginning of spring, when day and night are approximately equal in length.

Helium is used as a substitute for nitrogen in breathing gas mixtures for deep sea divers to prevent nitrogen narcosis and reduce breathing resistance under high pressure. Argon, xenon, and krypton are not commonly used for this purpose due to their physical properties and cost.

Water is approximately 50 times more viscous than gases such as air. This means water resists flow much more than gases do, making option C correct.

Gingivitis is an inflammation of the gums caused by bacterial infection, making the gums the part of the body affected by this disease.

The chemical formula for water is H2O, which consists of two hydrogen atoms bonded to one oxygen atom. This is a fundamental and well-known fact in chemistry.

Heparin is a natural anticoagulant present in the blood that prevents coagulation inside the body, ensuring blood flows smoothly within vessels. Haemoglobin carries oxygen, fibrin forms clots, and plasma is the liquid component of blood but does not prevent coagulation by itself.

LPG (Liquefied Petroleum Gas) primarily consists of propane and butane, with methane present only in very small amounts or as an impurity. Therefore, option D correctly lists methane, butane, and propane as the main components, with butane and propane being the major constituents.

Welding commonly uses gases like oxygen, acetylene, and argon. Oxygen and acetylene are used in oxy-acetylene welding, while argon is used as a shielding gas in processes like TIG welding. Hydrogen and nitrogen are not typical welding gases.

The length of the day is determined by Earth's rotation period and is not affected by atmospheric pollution levels. Therefore, an increase in atmospheric pollution does not change the length of the day.

When a force is transmitted through a string, it is called tension. Weight is the force due to gravity, momentum is mass times velocity, and torque is a rotational force, so tension is the correct term here.

Medium-sized kidney stones are commonly treated by lithotripsy, a procedure that uses shock waves to break stones into smaller pieces that can be passed naturally. Dialysis is unrelated to kidney stone removal, excretion is the natural process of elimination, and laser treatment is typically used for larger or more complex stones.

Balloons are commonly filled with helium because it is lighter than air, allowing the balloons to float. Nitrogen, oxygen, and argon are heavier or do not provide buoyancy like helium does.

Liquids that evaporate quickly are called volatile liquids because they have high vapor pressure and low boiling points, causing them to vaporize easily at room temperature.

Coal is a fossil fuel and is not renewable because it takes millions of years to form and cannot be replenished on a human timescale. Wind energy, solar energy, and hydroelectric power are all renewable sources as they rely on natural processes that are continuously replenished.

Hydrogen is the lightest element and substance among the options listed, having the lowest atomic mass and density.

The red color of tomatoes is due to lycopene, a red carotenoid pigment. Anthocyanins and xanthophylls are pigments responsible for other colors in plants but not the red color of tomatoes.

Stone is a solid because it has a fixed shape and volume, unlike water which is a liquid. Therefore, option B is correct.

Over-cooking food reduces its nutritional value by destroying heat-sensitive vitamins and nutrients, making option B the most accurate reason to avoid over-cooking. While over-cooking can affect digestibility and potentially produce harmful substances, the primary concern is nutrient loss.

Optical fibers are primarily used in communication systems because they can transmit data as light signals over long distances with minimal loss and high bandwidth.