How to run Whatsapp without app? My Samsung Tab is locked. It is only meant for educational purposes. My tab cannot run any app but only use Google through Wi-Fi. Tab can not use Sim card as well as it is locked by college authorities.  

So how can I run Whatsapp online on this tab?
Whatsapp web doesn't run standalone. It is an another frontend to an already installed and functioning Whatsapp session in a device. That is to say, if you have a device with Whatsapp already installed and connected to internet, then you can access it through Whatsapp Web as well (requires authentication from device). But the web functionality doesn't offer to create an account and use Whatsapp services so you're at loss here. 

More info: How do I use WhatsApp on my computer?