At show clearly how bonding occured in (cao)
Calcium
oxide

They both combine with The help of valency, which is the combining capacity of elements

Explanation:

I find it easier to understand valency as part of the Bhor’s model of an atom.

In his model, it was stated that electrons are spread around the nucleus in such a way that there are rings around the model. Each ring has a n value. So, k has 1, l has 2, m has 3 and n has 4...

what you need to know to find the number of electrons in each ring is to solve the formula 2n squared

Then, the valency is the 8 minus the number of electrons in the outermost shell. Remember that 8 is max number I;outer most shell. If you try it out for oxygen, you will get the value of 2 remaining, which can be gained if combined with calcium.

Hope it helps

hey there!

mass = 6.75 g

volume =   9 cm³

therefore:

d = mass / volume

d   = 6.75 / 9

d = 0.7 g/cm³

answer b