Chemistry - 3 (Railways - RRB)

The symbol for potassium is K.

Plasma is a fourth state of matter, which has the highest kinetic energy.

Mixture of sand and water can be separated by the methods of sedimentation and decantation.

Dead burnt plaster is CaSO₄.

The molecular formula of glucose is C₆H₁₂O₆.

Carbon is an essential element in all organic compounds.

Anhydrous ammonia is widely used in industrial refrigeration applications because of its high energy efficiency and low cost.

Graphite is an allotropic form of carbon which can be used as a lubricant.

0^oC = 273 K
6^oC = 273 K + 6 K = 279 K

In liquids, there is less space to move, so collisions are more frequent between the molecules causing a slower diffusion rate. The opposite happens in gases. There is more space in gases. As a result, there are less collisions between the molecules causing a faster diffusion rate. Other factors that may have an effect on diffusion rates are temperature, mass of the molecule, volume/surface area and the medium used.

Copper is a metal. It is solid in nature and thus, has the maximum intermolecular forces of attraction.

Glowing of an electric bulb is a physical change because when electric current is passed through the filament of a bulb, the filament starts glowing and the glow stops as soon as the current is cut off. The chemical composition of tungsten filament does not change.

Brass is an alloy of zinc and copper.

Evaporation is responsible for the cooling of water kept in an earthen pitcher during summer days.

Steam causes more severe burns than boiling water because of latent heat of vapourisation.

The flame of an LPG stove is blue in colour due to the complete combustion of LPG. When the LPG burns completely, the flame turns blue. Blue flame indicates dearest burning rate for a gas.

NaOH is used to make artificial fibre.

Turmeric turns red in colour in the presence of a base.

Diamond is not an isomer of graphite as diamond and graphite are the two allotropic forms of carbon.