Chemistry Fundamentals - Grade IX ICSE

Amorphous solids are substances that lack a long-range order or definite geometrical shape, unlike crystalline solids.

Absolute zero is defined as the theoretical temperature at which the entropy of a perfect crystal is zero and all molecular motion ceases. It is equivalent to 0 Kelvin or -273.15 degrees Celsius.

Atomicity refers to the total number of atoms present in one molecule of an element. For example, oxygen has an atomicity of 2 (O2).

Decantation is the laboratory process of separating a liquid from a solid sediment by carefully pouring the liquid out, leaving the solid behind. It relies on gravity to settle the particles.

Bleaching powder is chemically known as calcium hypochlorite, with the formula CaOCl2. It is widely used for disinfection and bleaching purposes.

Hygroscopic substances are materials that attract and hold water molecules from the surrounding environment through absorption or adsorption. This often results in the substance becoming damp or liquid.

Ductility is the physical property of a metal that allows it to be stretched or drawn into a thin wire without breaking. Malleability, by contrast, refers to the ability to be hammered into thin sheets.

An electrolyte is a substance that produces an electrically conducting solution when dissolved in a polar solvent, such as water. The dissolved electrolyte separates into cations and anions, which disperse uniformly through the solvent.

Fluorine, chlorine, bromine, and iodine belong to Group 17 of the periodic table, which are collectively known as the halogens. They are highly reactive non-metals.

A solution containing one gram molecular weight (one mole) of solute in one litre of solution is defined as a molar solution. The term 'Gram molecular solution' is a synonym for a 1 Molar solution.

Deliquescence is the process where a substance absorbs so much moisture from the atmosphere that it dissolves in the absorbed water to form a solution. This is a more extreme form of being hygroscopic.

Methane is commonly known as marsh gas because it is produced naturally in marshes and wetlands by the anaerobic decomposition of organic matter.

Phenolphthalein (misspelled as 'Phenolpthalin') and methyl orange are pH indicators that change color depending on acidity or alkalinity. Phenolphthalein is colorless in acid and pink in base, while methyl orange is red in acid and yellow in base. Catalysts, electrolytes, and enzymes are different types of chemical substances.

Ionization is the process by which an atom or a molecule acquires a negative or positive charge by gaining or losing electrons, often in the context of dissolving in a solvent like water.

Quenching is a heat treatment process where a metal is heated to a high temperature and then rapidly cooled, usually in water or oil, to increase its hardness.

A molecular formula represents the actual number of atoms of each element present in one molecule of a compound, unlike an empirical formula which only shows the simplest ratio.

Chemical analysis is the process of breaking down a compound into its constituent elements or simpler substances to determine its composition.

Occlusion is the specific term used when gases are adsorbed onto the surface of finely divided metals, such as palladium or platinum.

Standard atmospheric pressure is defined as 760 mm of mercury (Hg) at 0 degrees Celsius.

Tollens reagent is a chemical reagent used to detect aldehydes, consisting of a solution of silver nitrate and ammonia.

Precipitation is the formation of an insoluble solid (precipitate) when two clear solutions are mixed, typically due to a chemical reaction.

Absolute temperature in Kelvin is calculated by adding 273.15 (commonly rounded to 273) to the temperature in degrees Celsius.

Diffusion is the process of spontaneous movement of particles from an area of higher concentration to an area of lower concentration, resulting in the mixing of substances.

Bronze is an alloy consisting primarily of copper, usually with tin as the main additive. While compositions vary, the description provided matches the general definition of bronze.