Chemistry Class 12 NCERT Solutions: Chapter 1 The Solid State Part 8
Q: 15. Copper crystallises into a fcc lattice with edge length . Show that the calculated density is in agreement with its measured value of .
As the lattice is fcc type, the number of atoms per unit cell,
We also know that,
Applying the relation:
The measured value of density is given as . Hence, the calculated density is in agreement with its measured value.
Q: 16. Analysis shows that nickel oxide has the formula . What fractions of nickel exist as ions?
The formula of nickel oxide is .
Therefore, the ratio of the number of Ni atoms to the number of O atoms
Now , total charge on
Let the number of is .
Now, total charge on
And, total charge on
Since, the compound is neutral, we can write:
Therefore, number of ions
And, number of ions
Hence, fraction of nickel that exists as
And, fraction of nickel that exists as
Alternatively, fraction of nickel that exists as