The bond angle and hybridization in ether $(CH_3OCH_3)$ is

$\frac{\sin 1^{\circ}+\sin 2^{\circ}+\ldots+\sin 89^{\circ}}{2(\cos 1^{\circ}+\cos 2^{\circ}+\ldots+\cos 44^{\circ})+1} = $

Amongst the given taxonomic aids,how many are associated with the preservation of specimens?
Monograph,Flora,Key,Museums,Botanical Gardens,Catalogue,Herbarium,Manual

The point of intersection of the diagonals of a square is at the origin,and the coordinate axes are drawn along the diagonals. If the side length of the square is $a$,which of the following is $NOT$ a vertex of the square?

$A$ cubical block of wood with a side length of $10 \, cm$ floats at the interface between oil and water,with its lower surface horizontal and $4 \, cm$ below the interface. The density of oil is $0.6 \, g \cdot cm^{-3}$ and the density of water is $1 \, g \cdot cm^{-3}$. The mass of the block is ...... $gm$.

The most popularly known blood grouping is the $ABO$ grouping. It is named $ABO$ and not $ABC$,because '$O$' in it refers to having