2Ni(OH) → Ni2O + H2O
How many moles of water forms from 4.20 mol of nickel (I) hydroxide?

2.1 moles of water formed.

Explanation:

Given data:

Moles of water formed = ?

Moles of Ni(OH) = 4.20 mol

Solution:

Chemical equation:

2Ni(OH)    →  Ni₂O + H₂O

Now we will compare the moles of Ni(OH)  with water.

             Ni(OH)           :            H₂O

                2                 :              1

              4.20             :            1/2×4.20 = 2.1 mol

2.1 moles of water formed.

3 1/4 %

explanation:

hey there!

mass = 6.75 g

volume =   9 cm³

therefore:

d = mass / volume

d   = 6.75 / 9

d = 0.7 g/cm³

answer b