No SD card in tablet, but a few of my Apps were "sent" to "my SD" card

Please explain why some apps, also my FB acc was sent to my "SD Card", while there is not one inserted in my tablet.
And now I can not go into my FB acc and the other Apps that was sent there.
Please advise if there is a hacker on my tablet.
I installed a new FB and its also a katana version 100.0.0.20.70. Is this safe????
Thx

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