Chemistry (Part-IX) (Railway)

A cyclic unsaturated carbon compound has a ring structure with at least one double or triple bond between the carbon atoms.

• In benzene, (C₆H₆) six carbon atoms form a ring structure and there are three single bonds and three double bonds between the carbon atoms.

• Hence, benzene can be taken as an example of a cyclic unsaturated carbon compound.

A double displacement reaction is a type of reaction in which two reactants exchange ions to form two new compounds.

• CuSO₄ + H₂S → CuS + H₂SO₄ is an example of such a reaction.

• This is because Cu₂⁺ displaces S₂⁻ (sulphide ions) from hydrogen sulphide, and H⁺ displaces SO₄²⁻ (sulphate ions) from copper sulphate solution.

A more reactive metal displaces a less reactive metal from salt solution in a displacement reaction.

• For example, in Zn(s) + CuSO₄(aq) → ZnSO₄(aq) + Cu(s), zinc has the ability to displace copper from its respective salt solution.

The breakdown of pyruvate using O₂ takes place in the mitochondria matrix.

• When glucose gets converted to pyruvate by glycolysis, only a small fraction of the total free energy potentially available from the glucose is released.

• In mitochondria, when the metabolism of sugars is completed, the pyruvate is imported into the mitochondria and oxidized by O₂ to CO₂ and H₂O.

Barium Oxide (BaO) is the oxide of Barium.

• Potassium Oxide (K₂O) is the oxide of Potassium.

• It is an ionic compound of potassium and oxygen.

Calcium oxychloride, Ca(OCl)₂, is known as bleaching powder.

• It is produced industrially by treating lime, Ca(OH)₂, with chlorine gas.

• 2Cl₂ + 2Ca(OH)₂ → Ca(OCl)₂ + CaCl₂ + 2H₂O

Carbon monoxide reacts with hydrogen under certain conditions to form methanol (CH₃OH).

• CO(g) + 2H₂(g) → CH₃OH(l)

Insects respire through a system of openings on the skin called spiracles and an associated network of tubules called tracheae.

• The air enters the body of an insect through spiracles and then is circulated through the network of the tracheae where gaseous exchange takes place directly with the insect tissues.