The correct order of the number of unpaired electrons in the given complexes is

A. $$\left[\mathrm{Fe}(\mathrm{CN})_{6}\right]^{3-}$$

B. $$\left[\mathrm{Fe} \mathrm{F}_{6}\right]^{3-}$$

C. $$\left[\mathrm{CoF}_{6}\right]^{3-}$$

D. $$\left.[\mathrm{Cr} \text { (oxalate})_{3}\right]^{3-}$$

E. $$\left[\mathrm{Ni}(\mathrm{CO})_{4}\right]$$

Choose the correct answer from the options given below:

The correct relationships between unit cell edge length '$$a$$' and radius of sphere '$$r$$' for face-centred and body-centred cubic structures respectively are :

Number of water molecules in washing soda and soda ash respectively are :

The reaction used for preparation of soap from fat is :