General Science - 1

Distillation is the process of heating sea water to create steam, which is then condensed to form pure water, leaving salts behind. Filtration and evaporation are not sufficient to remove dissolved salts effectively.

Indigo is a natural vat dye, not an azo dye. Azo dyes contain the N=N group, which indigo does not.

A catalyst is defined as a substance that increases the rate of a chemical reaction without being consumed in the process.

Rust is a hydrated iron oxide, typically represented as a mixture of hydrated ferrous and ferric hydroxides or oxides formed in the presence of oxygen and moisture.

Chlorination is the standard method for disinfecting water supplies to kill bacteria and other pathogens.

Soap is produced through saponification, which involves reacting fats or oils (like linseed oil) with a strong base like caustic soda (sodium hydroxide).

Iron ore (usually oxides like hematite) is converted to metallic iron by removing oxygen, which is a reduction process using carbon or carbon monoxide.

Photographic film contains silver halides (like silver bromide) which decompose upon exposure to light; black paper prevents this premature exposure.

Dolomite is a carbonate mineral composed of calcium magnesium carbonate, CaMg(CO3)2, making it an important ore for magnesium.

The Haber process produces ammonia, which is primarily used to manufacture nitrogen-based fertilizers like urea and ammonium nitrate.

For aquatic life to survive, the dissolved oxygen level in water should generally not fall below 4 mg/L.

Hard water contains calcium and magnesium ions that react with soap to form insoluble precipitates (scum) instead of lather.

Synthetic detergents are typically sodium salts of long-chain alkyl benzene sulphonic acids or similar compounds, which do not form scum with hard water.

Aluminium is widely used in domestic appliances due to its light weight, corrosion resistance, and good thermal conductivity.

The pH scale is a logarithmic measure of the concentration of hydrogen ions in a solution, indicating its acidity or basicity.

Producer gas is a mixture of carbon monoxide (CO) and nitrogen (N2), produced by passing air over red-hot coke.

In photography, 'hypo' solution is used as a fixing agent to dissolve unexposed silver halides, and its chemical name is sodium thiosulphate.

Benzoic acid and its salts (like sodium benzoate) are widely used as food preservatives because they inhibit the growth of mold and bacteria.

Aspirin is the common name for acetylsalicylic acid, which is synthesized by the acetylation of salicylic acid.

Diesel engines are more efficient and provide better fuel economy than gasoline engines, making them ideal for heavy-duty applications.

DNA stores genetic information (heredity) and provides the instructions for protein synthesis. It does not directly release energy; that is the role of metabolic processes like cellular respiration.

Nanotechnology involves manipulating matter at the nanoscale, typically 1-100 nm (10^-9 m). Drug delivery is a major application of nanodevices, but it is a specific use case rather than the underlying physical definition of the field.