What is the density of an element (At mass 100 g mol$$^{-1}$$) having BCC structure with edge length 400 pm?

In which of the following salts, the solubility increases appreciably with increase in temperature?

What is effective atomic number of cobalt in [Co(NH$$_3$$)$$_6$$]$$^{3+}$$ if Co(Z = 27) ?

Which among the following is NOT an example of one-dimensional nanostructure?