Statement A: A zener diode is always connected in reverse bias to use it as voltage regulator.  

Statement B: The potential barrier of a p-n junction lies between 0.1 to 0.3 V , approximately. 

A is correct and B is wrong

When Zener diode is forward biased, it behaves like ordinary diode and when reverse biased, it will be a voltage stabilizer. Also, at room temperature, the voltage across the depletion layer for silicon is about 0.6−0.7V and for germanium is about 0.3−0.35V .