Everyday Science

Mars is known as the 'Red Planet' because of the iron oxide (rust) on its surface, which gives it a reddish appearance when viewed from Earth.

Brass gets discoloured in air primarily due to the presence of hydrogen sulphide gas, which reacts with the copper in brass to form copper sulphide, causing tarnishing and discoloration.

Composting is the biological process of converting wet organic waste into manure or nutrient-rich soil conditioner through decomposition by microorganisms.

Silicon-based compounds, such as silicones, are commonly used in beauty parlours for hair setting because they provide smoothness, shine, and hold to the hair. Sulphur, chlorine, and phosphorus are not typically used for hair setting purposes.

Silver is the best conductor of electricity among metals, better than copper, gold, and lead, making it the purest conductor in terms of electrical conductivity.

Conversion of water into steam is a physical change, not a chemical reaction, because it involves a change in state without altering the chemical composition. The other options involve chemical changes where new substances are formed.

The breath test for drunken driving commonly uses potassium permanganate in sulfuric acid to oxidize ethanol in the breath, causing a color change that indicates alcohol presence. Potassium dichromate is also used in some breath analyzers but the classical chemical test is with potassium permanganate-sulfuric acid.

The instrument specifically used for viewing the Sun safely is called a solar telescope (also historically called a heliograph or photoheliograph). However, the term 'heliograph' in modern usage primarily refers to a signaling device that uses sunlight reflection to send messages, not an instrument for viewing the Sun. The options given include 'Stroboscope' (used to view fast-moving objects), 'Heliograph' (signaling device), 'Solograph' (not a recognized instrument), and 'None of these'. Since none of the options correctly name a solar telescope or a proper solar viewing instrument, the correct answer is 'D' (None of these). Viewing the Sun requires specialized solar telescopes or filters to protect the eyes, which are not represented by the other options.

Black soil is also known as Regur soil, which is rich in lime, iron, magnesia, and alumina. It is particularly suitable for growing cotton and is found in regions like the Deccan Plateau in India.

Naphthalene sublimes, turning directly from solid to gas, while sand does not. This property allows separation of the mixture by sublimation, leaving sand behind.