Why did the Raspberry Pi foundation select "BCM 2835" and not any other SOC for Raspberry Pi? Is any other SOC possible ? If yes , which ?
The developers of the Pi had some connection with broadcom. That's why they choose Broadcom.
There are a lot of SoCs that run ARMv6 (like the Pi) and the more recent ARMv7. Also note that a lot of linux distributions are dropping support for ARMv6