Fe

Zn

K

Ca

They are used as cation exchangers.

They have open structure which enables them to take up small molecules.

Zeolites are aluminosilicates having three dimensional network.

Some of the SiO$$_4^{4 - }$$ units are replaced by AlO$$_4^{5 - }$$ and AlO$$_6^{9 - }$$ ions in zeolites.

Among halide ions, iodide is the most powerful reducing agent.

Fluorine is the only halogen that does not show a variable oxidation state.

HOCl is a stronger acid than HOBr.

HF is a stronger acid than HCl.

B(OH)₃

PO(OH)₃

SO(OH)₂

SO₂(OH)₂