Is the "BX cable" supposed

What i think your saying is that you purchased a brand new cooktop and their is no cable with it to connect to the power supply?
It doesn't have to be there sometimes it is and other times their is just a juntion box and you need to run the house wiring into the junction box

I have found them both ways....are there wires hanging out or is it ready to be direct wired... this is often the clue to whether the BX is included or not...if you have wires then there should be BX... if not wires then they are planning on it being direct wired by your electrician...