Which element does not belongs to 3rd group? Boron is non metal whereas aluminum is metal, it is due to? Increase in atomic size in 3rd group is not regular, it is due to? One of the feature of boron is its ability to form? Borax is a white crystalline solid and it is? Boron does not form stable cation due to? Corundum is the most abundantly found mineral of? The metal used in thermite process because of its activity is?