Everyday Science

Pumice stone is a volcanic rock that contains many air pockets, making it less dense than water and allowing it to float. Other stones like limestone, basalt, and quartzite are denser and sink in water.

The mass of the Earth is approximately 5.972 × 10^24 kilograms, which is the widely accepted scientific value. The other options are incorrect values.

Honey is primarily composed of sugars, with fructose being the major component, followed by glucose. This high fructose content gives honey its characteristic sweetness.

Water exhibits a maximum density at approximately 4°C, which is a unique property among common substances. Ice, benzene, and chloroform do not have a density maximum at typical conditions.

Alexander Graham Bell is credited with inventing the telephone in 1876, making option D the correct answer. The other options are notable inventors but not related to the invention of the telephone.

Dry ice is the solid form of carbon dioxide (CO2). It sublimates directly from solid to gas at atmospheric pressure without becoming liquid, making 'Solid Carbon Dioxide' the correct chemical name.

The surface temperature of the Sun, also known as the photosphere temperature, is approximately 5,778 Kelvin, which is the widely accepted scientific value.

The Earth's atmosphere is commonly divided into five main layers: the troposphere, stratosphere, mesosphere, thermosphere, and exosphere. This classification is standard in atmospheric science.

Rain-proof coats and tents owe their waterproof properties primarily to the surface tension of water and the waterproof coatings or membranes applied to the materials. Surface tension causes water to bead up and not penetrate the fabric easily. Additionally, materials are treated with waterproof coatings (such as polyurethane or silicone) or use membranes like Gore-Tex that block water penetration while allowing breathability. This combination of surface tension effects and specialized coatings or membranes makes rain-proof coats and tents water-resistant or waterproof. Other options like viscosity, specific gravity, and elasticity do not contribute to waterproofing in this context.

Most of the ozone in Earth's atmosphere is concentrated in the stratosphere, forming the ozone layer which absorbs and scatters ultraviolet solar radiation.

Metrology is the scientific study of measurement, including its methods, units, and accuracy. The other options refer to different fields: Entomology is the study of insects, Ichthyology is the study of fish, and Ecology is the study of organisms and their environment.

Soft drinks are made with chilled water because cold water can dissolve and retain more carbon dioxide gas than water at room temperature, which helps maintain the drink's fizziness and taste.

In an oil lamp, the oil rises up the wick due to capillary action, which is the ability of a liquid to flow in narrow spaces without the assistance of external forces. This phenomenon allows the oil to move upward against gravity through the tiny pores in the wick.

An echo is the reflection of sound waves from a surface back to the listener, which is why option A, Reflection, is correct.

Tocopherol is the chemical name for vitamin E, which is a fat-soluble antioxidant important for protecting cell membranes from oxidative damage.

The density of milk typically ranges around 1.03 to 1.04 g/cm³ depending on fat content and temperature. Among the given options, 1.034 g/cm³ is the most accurate average value for milk density.

There are 24 standard time zones in the world, each generally corresponding to one hour difference in time, covering the 24 hours of the day.

UPS stands for Uninterruptible Power Supply, a device that provides backup power to electronic devices during power outages, which is why it is widely used in households.

Iodised salt contains potassium iodide or potassium iodate, which are iodine salts of the metal potassium. This is done to prevent iodine deficiency disorders.

Cabbage contains sulfur compounds such as glucosinolates, which are responsible for its characteristic smell and health benefits. The other vegetables listed do not notably contain sulfur.

Nichrome is commonly used as the heating element in electric heaters because it has high electrical resistance and can withstand high temperatures without oxidizing quickly. Tungsten and graphite are used in other applications, while chromium alone is not typically used as a heating element.

Vitamin B complex includes several vitamins (B1, B2, B3, B5, B6, B7, B9, B12) found in a variety of foods. Seafood is a rich source of many B vitamins, especially B12. However, other B vitamins are also found in fruits, vegetables, seeds, legumes, dairy, meat, and fortified cereals. While seafood is an excellent source of vitamin B12, other B vitamins are widely distributed in plant and animal foods. Thus, seafood is a correct and primary source of vitamin B complex, particularly B12, but other options also contain some B vitamins. The question's answer 'A' (Sea Foods) is correct as the best single choice among the options given.

Rayon is a synthetic fiber made from regenerated cellulose and is commonly known as artificial silk due to its silk-like appearance and texture. Nylon and Terylene are synthetic fibers but do not resemble silk, and cotton is a natural fiber.

Chlorine is commonly used in water purification to kill harmful bacteria and pathogens, making water safe to drink. Bromine is less commonly used, plants do not purify water chemically, and 'Young man' is irrelevant.

Carbon monoxide is highly toxic because it binds to hemoglobin in the blood more effectively than oxygen, preventing oxygen transport and leading to poisoning. The other gases listed are either non-toxic or less harmful at typical exposure levels.