Answer:
Solid ionic compounds do not conduct electricity because the ions are held firmly in place. The ions cannot move to conduct the electric current. But when an ionic compound melts, the charged ions are free to move. Therefore, molten ionic compounds do conduct electricity.
Answer : The maximum amount of nickel(II) cyanide is 
Explanation :
The solubility equilibrium reaction will be:

Initial conc. 0.220 0
At eqm. (0.220+s) 2s
The expression for solubility constant for this reaction will be,
![K_{sp}=[Ni^{2+}][CN^-]^2](https://tex.z-dn.net/?f=K_%7Bsp%7D%3D%5BNi%5E%7B2%2B%7D%5D%5BCN%5E-%5D%5E2)
Now put all the given values in this expression, we get:


Therefore, the maximum amount of nickel(II) cyanide is 
Answer: 0.600 moles
Balanced eqn for decomposition of the rocket fuel:
2 NH4ClO4 (s) ----> N2 (g) + Cl2 (g) + 2 O2 (g) + 4 H2O (g)
Since, 2 moles of NH4ClO4 produces 2 moles of O2 gas, this means that 0.6 moles of NH4ClO4 will produce 0.6 moles of O2 gas
Protons and neutrons exist within the neucleus, while electrons do not.