Answer:

Explanation:
At
, the heat of vaporization of water is given by:

The water here condenses and gives off heat given by the product between its mass and the heat of vaporization:

The block of aluminum absorbs heat given by the product of its specific heat capacity, mass and the change in temperature:

According to the law of energy conservation, the heat lost is equal to the heat gained:
or:

Rearrange for the final temperature:

We obtain:

Then:

The coordination number is 6. The outer Cl- ion isn't included, so you count 4 x NH3 and 2 x Cl- are within Co's coordination sphere.
I think it’s the third option