ICSE 2025 Chemistry Specimen Paper

The process of coating a metal object with a thin layer of another metal using an electric current. The object to be plated acts as the cathode, while a plate of the plating metal acts as the anode.

The chemical reaction that occurs at the cathode during electroplating where metal ions in the electrolyte gain electrons and deposit as a solid metal layer on the object being plated.

The observation of a shiny, metallic coating forming on the surface of the object being electroplated.

The concentration of copper ions in the electrolyte remains constant during electroplating, as copper ions are replenished from the anode by dissolving copper metal, ensuring a continuous supply of copper ions for the plating process.

A type of chemical bond where two atoms share a pair of electrons, with both electrons being provided by the same atom.

A salt formed by the complete neutralization of an acid by a base, containing no excess of either acid or base.

A reaction in which a hydrogen atom in an alkane molecule is replaced by a halogen atom.

The energy required to remove one electron from a neutral gaseous atom in its ground electronic state.

A homogenous mixture of two or more metals, or a metal and a non-metal, in a definite proportion, usually in molten state.

The process where a carbonate ore is heated strongly in the absence of air to drive off carbon dioxide, leaving the metal oxide behind.

An element with one electron in its outermost shell, meaning it has a large atomic size due to weak attraction between the nucleus and the outermost electron.

Hydrochloric acid, HCl, does not form acid salts because it can only donate one proton (H+) per molecule.

The addition reaction involves adding atoms or groups of atoms across the double or triple bond in a molecule.

A solution that is acidic will turn methyl orange solution pink or red.

The empirical formula represents the simplest whole-number ratio of atoms of different elements in a compound.

The ratio of the volumes occupied by gases at the same temperature and pressure is directly proportional to the ratio of their moles.

The oxidizing electrode is the electrode where oxidation takes place, losing electrons.

An element with a greater electron affinity tends to have a stronger oxidizing power, meaning it is more likely to gain electrons and oxidize other elements.

An element with greater electron affinity is more likely to attract electrons, thus having higher electronegativity.

Elements with higher electron affinities tend to be placed to the right of the periodic table, as electronegativity increases across a period.

Metal atoms tend to have a maximum of 1-3 electrons in their outermost shell, as they easily lose electrons to achieve a stable noble gas configuration.

A reducing agent is a substance that loses electrons and causes another substance to gain electrons (be reduced).

The process of converting ammonia to nitric acid through a series of steps, involving the catalytic oxidation of ammonia to nitrogen oxides and subsequent reactions to form nitric acid.

The temperature and catalyst required during the catalytic oxidation of ammonia in the Ostwald's process are 800-900°C and platinum-rhodium gauze, respectively.

The balanced chemical equation for the conversion of nitrogen dioxide to nitric acid in the Ostwald's process is: 3NO2 + H2O → 2HNO3 + NO.

A substance that loses electrons during a chemical reaction is called a reducing agent, which is the substance being oxidized.

The balanced chemical equation for the reaction of ammonia with heated copper oxide, demonstrating ammonia's reducing property, is: 2NH3 + 3CuO → N2 + 3Cu + 3H2O.

An alloy made up of copper, zinc, and tin, known for its strength and corrosion resistance, is called bronze.

An alloy made up of lead and tin, known for its low melting point and ability to be easily melted and shaped, is called solder.

A reddish-brown gas, nitrogen dioxide (NO2), is evolved when a nitrate containing a cation that forms an insoluble oxide is heated strongly.

The chalky white insoluble precipitate formed when excess ammonium hydroxide is added to a solution of a lead salt is lead hydroxide, Pb(OH)2.