Answer
The name of $Mn(OH)_2$ is: "Manganese (II) hydroxide".
Work Step by Step
1. Identify the positive ion, and name it.
$Mn^{2+}$ is the positive ion.
So, the first name of the compound will be: "Manganese (II)";
** Most of the transition metals have more than 1 ion, so we must put a number to indicate the charge.
2. Identify the negative ion, and name it.
$OH^-$ is the negative ion.
As we can see in Table 2.2 (Page 58), this ion is called "hydroxide".
3. Putting those two names together:
Manganese (II) hydroxide.
