Boric acid on heating above 170C gives metaboric acid, which on further heating above 300C gives tetraboric acid (or boric acid). Boric acid may sometimes refer to any of these acids. On further heating gives boron trioxide.
2 4 2
When orthoboric acid is heated above 170⁰C it gives meta boric acidwhich on furthur heating above 300⁰C gives tetra boric acid and on futher heating gives boron trioxide.
1 5 1