df[df['column name'].isna()]
df[df.isnull().any(axis=1)]
df[df['Col2'].isnull()]
np.count_nonzero(df.isnull().values)
np.count_nonzero(df.isnull()) # also works
df[df['column name'].isnull()]
selected_rows = df[~df['Age'].isnull()]
# Try using a loc instead of a where:
df_sub = df.loc[df.yourcolumn == 'yourvalue']
df[df["A_col"].isnull()]