The coordination number of Nickel in [Ni (C₂O₄)]⁻⁴ is 6.

Oxalate is an example for bidentate ligand, three oxalate ligands form sixcoordinate bonds around the Ni²⁺ ion.

Since C₂O₄⁻³ is a bidentate ligand and these ligands are 3 in number. So, co-ordinate number of Nickel in [Ni (C₂O₄)₃]^4- is: 3 x 2 = 6 

Chondrichthyes: These are marine animals with a streamlined body and cartilaginous endoskeletal. A placental mammal (subclass Eutheria), any member of the mammalian group, is recognized by the presence of a placenta, which facilitates the exchange of nutrients and wastes between the blood of the mother and the fetus. Invertebrates include all living mammals, except marsupials and monotremes. Cyclostomes are marine, but they migrate to fresh water for spawning. After spawning, within a few days, they die. After metamorphosis, their larvae return to the ocean. Kilons and testudos (reptiles) are not able to maintain a constant body temperature.

Pusa Komal is a crop variety of cowpea. It is resistant to bacterial blight.

All cultivated cowpeas are found within the universally accepted V. unguiculata subspecies unguiculata classification, which is then commonly divided into four cultivar groups: unguiculata, biflora, sesquipedalis, and textiles.

Compound is β -hydroxy aldehyde hence the reaction is aldol addition. A and B can be known by retro aldol addition as follows:

Hypanthodium is a special type of inflorescence. Here, the receptacle is fleshy and forms hollow ball like structure with an apical opening. Three types of flowers develop on the inner surface of the receptacle. The female flowers are towards the base, male flowers are towards the orifice and short styled sterile female flowers are in between, For example: Ficus sp. The inflorescence is pollinated by a gall wasp.

Ecosystem diversity deals with the variations in ecosystems within a geographical location and their overall impact on human existence and the environment. Ecological diversity is a type of biodiversity. It is the variation in the ecosystems found in a region or the variation in ecosystems over the whole planet.

Polyacrylonitrile is a synthetic polymer with the linear formula (C₃H₃N)_n. Although it is thermoplastic it does not melt under normal conditions, since it degrades before melting at above 300 °C. Almost all Polyacrylonitrile resins are copolymers made from mixtures of monomers, with acrylonitrile as the main component. As it is a non condensation polymer.