\(n_{Cu\left(NO_3\right)_2}=0.1\cdot1=0.1\left(mol\right)\)
\(n_{KOH}=0.25\left(mol\right)\)
\(Cu\left(NO_3\right)_2+2KOH\rightarrow Cu\left(OH\right)_2+3KNO_3\)
\(0.1....................0.2.................0.1\)
\(\Rightarrow KOHdư\)
\(m_{Cu\left(OH\right)_2}=0.1\cdot98=9.8\left(g\right)\)