Railway Science (Chemistry-Miscellaneous) (Part-II)

General electronic configuration of d-block elements is (n−1) d¹⁻¹⁰ ns¹⁻² .
d-block elements (also known as transition elements) exhibit transitional behavior between highly reactive ionic compound forming s-block elements on one side, and mainly the covalent compound forming p-block elements on the other side.
Transition elements show the properties of variable valency, colored ions, complex formation, paramagnetic behavior, catalytic ability and pronounced metallic character.

An increase in humidity would actually decrease the rate of evaporation while vice-versa would increase the rate of evaporation. Similarly, an increase in wind speed and temperature would increase the rate of evaporation.
Evaporation converts matter from its liquid state to a gas.
Vaporization converts matter from a liquid or a solid to a gas. Humidity : The concentration of water vapor present in the air is known as humidity.

Calorific value : The amount of heat produced by unit volume of a substance by complete combustion. Unit of calorific value - kilojoule per kilogram (KJ/Kg). Volatile matter of fuel : Those components of fuel which are readily burnt in the presence of oxygen.
Ignition temperature of fuel : The minimum temperature to which a fuel must be heated so that it may catch fire and start burning. Thermal capacity : The quantity of heat necessary to produce a unit change of temperature in a unit mass of a material.

There are four types of ore separation based on the nature of the ore: Froth floatation process is based on the different wetting nature of ore and gangue particles. Mustard oil is used as frother in the froth flotation process.
Magnetic separation is based on the principle of magnetic properties of the components of the ore. Leaching is a chemical process that involves the selective dissolution of metals or minerals from their ores or concentrates using a suitable solvent.

Mole - The mole is the unit of measurement for amount of substance, a quantity proportional to the number of elementary entities of a substance. Molecular weight of H₂O = 1(2) + 16 = 18 grams.

Freezing - The process through which a substance changes from a liquid to a solid. Titration - A technique where a solution of known concentration is used to determine the concentration of an unknown solution. Blending - The action of mixing or combining things together.

Gold {Symbol: Au, Atomic number (Z)=79} : Resistant to most acids, though it does dissolve in aqua regia. The gold content of gold alloys is measured in carats (k), pure gold is designated as 24k.
Osmium (Os, Z=76): Densest element. Hydrogen (H, Z=1): Lowest density. Mercury (Hg, Z=80): Commonly-known as ‘quicksilver’ and was formerly named ‘hydrargyrum’. It is the only metallic element that is liquid at room temperature.
Copper (Cu, Z = 29): The first metal used by man. Iron (Fe, Z = 26): Wrought Iron (Purest form) and the Pig Iron (the most impure form).

Carbon monoxide (CO) - Contains approximately 1.33 g of oxygen for each 1.00 g of carbon. Carbon dioxide (CO₂) - It is a colorless gas. Solid Carbon-di-oxide is also known as ‘Dry Ice’.
Methane (CH₄) - It is flammable and used as fuel. It is also known as ‘Marsh Gas’ and ‘Damp Fire’. Nitrogen dioxide (NO₂) - It is a reddish-brown gas with a pungent odor.

Graham's Law of Diffusion : At constant temperature and pressure, the rate of diffusion of a gas is inversely proportional to the square root of its density (or) Vapor pressure (or) molecular weight. The rate of diffusion depends on factors such as temperature, pressure and density of the particles involved.

Silver chloride turns grey in sunlight to form silver metal. This is due to the decomposition of silver chloride into silver and chlorine by light.
Chemical reaction: 2AgCl (s) → 2 Ag (s) + Cl₂ (g). This reaction is used in black and white photography.