Gunnah
There are three types of gunnah :
a. Nun Sakin b. Mim Sakin c. Wajib Gunnah
a. Nun sakin
If after Nun Sakin or Tanween there appears any of the following 8 letters, there will be no gunnah. ء . ه. ع. ح . غ . خ. ر. ل
Ex: مِنْ هٰذِهٖ
If there any other letter then there will be gunnah.
Ex: اِنْ كُنْتُمْ
b. If after Meem sakin there comes ب orم make gunnah.
Ex: تَرۡمِيۡهِمۡ بِحِجَارَةٍ
If there any other letter then there will be no gunnah.
Ex: كَيۡدَهُمۡ فِيۡ تَضۡلِيۡلٍ
c. When the letters Nun or Mim have a Tashdid on them, they should be pronounced with Gunnah.
Ex: اِنَّ