Assalamu Alaikum
This is the answer from Shaykh:
The
ismu jinsin jam"iyyun is used both as feminine singular and as masculine singular. See the use of the word
nakhl (
نَخْل) meaning date palms in the Quran. In suurat al-Qamar (54:20) it is treated as masculine singular: a"jaazu nakhlin
munqa"ir.
تَنزِعُ النَّاسَ كَأَنَّهُمْ أَعْجَازُ نَخْلٍ مُّنقَعِرٍ
And in suurat al-Haaqqah (69:7) it is treated as feminine singular: a"jaazu nakhlin
khaawiyah.
سَخَّرَهَا عَلَيْهِمْ سَبْعَ لَيَالٍ وَثَمَانِيَةَ أَيَّامٍ حُسُومًا فَتَرَى الْقَوْمَ فِيهَا صَرْعَى كَأَنَّهُمْ أَعْجَازُ نَخْلٍ خَاوِيَةٍ
The word for apples is tuffaaH. You may say: haadhihii tuffaaH, or haadhaa tuffaaH. The second is the more common.
'Three apples' is 'thalaathu tuffaaHaatin' just as we say: 'thalaathu tamaraatin.'
Wassalam,
VAR