Na₂B₄O₇ .10H₂O + H₂SO₄ (conc.)\(\rightarrow\) Na₂SO₄ + H₂B₄O₇ + 10H₂O
Borax
H₂B₄O₇ + 5H₂O \(\rightarrow\)  4H₃BO₃
                              Boric acid
2H₃BO₃ \(\xrightarrow[]{Heat}\) B₂O₃ + 3H₂O
                         Boric oxide
B₂O₃ + 3Mg \(\xrightarrow[]{\triangle}\)2B + 3MgO

(a) Being acidic B₂O_3,Sio₂ and CO₂ react with alkalis to form salts
\(B_{ 2 }O_{ 3 }+2NaOH\rightarrow 2NaBO_{ 2 }+H_{ 2 }O\\ Boric\quad \quad \quad \quad \quad \quad sodium\quad metaborate\\ anhydride\)
\(SiO_{ 2 }+2NaOH\underrightarrow { D } Na_{ 2 }CO_{ 3 }+H_{ 2 }O\)
\(\\ Silica\quad \quad \quad \quad \quad \quad \quad \quad \quad Sodium\quad carbonate\\ CO_{ 2 }+2NaOH\rightarrow Na_{ 2 }CO_{ 3 }+H_{ 2 }O\\ Carbon\quad dioxide\quad \quad \quad sodium\quad carbonate\quad \quad \quad \quad \)
(b) Being amphotric, Al₂O₃ and PbO₂ react with both acids and bases.
\(Al_{ 2 }O_{ 3 }+3H_{ 2 }SO_{ 4 }\rightarrow Al_{ 2 }(SO)_{ 4 }+3H_{ 2 }O\)
\( Al_{ 2 }O_{ 3 }+2NaOH\overset { fuse }{ \rightarrow } \ 2NaAlO_{ 2 }+H_{ 2 }O\)
\(\\ Alumina\quad \quad \quad \quad \quad \quad \quad sodium\quad metaaluminate\\ 2PbO_{ 2 }+2H_{ 2 }SO_{ 4 }\rightarrow 2PbSO_{ 4 }+2H_{ 2 }O+O_{ 2 }\)
\(\\ PbO_{ 2 }+2NaOH\rightarrow Na_{ 2 }PbO_{ 3 }+H_{ 2 }O\\ Lead \ dioxide\quad \quad Sodium \ plumbate\)
(c) Being basic,Tl₂O₃ reacts with acid
\(Tl_{ 2 }O_{ 3 }+6HCl\rightarrow 2TICl_{ 3 }+3H_{ 2 }O\)

In this reaction, diborane is obtained 
aNaBH₄ +I₂\(\rightarrow\)B₂H₆ + 2NaI + H₂

BF₃ being a Lewis acid accepts a pair of electrons from NH₃ to form the corresponding complex.
F₃B                   NH₃\(\rightarrow\)       F₃B\(\leftarrow\)NH₃
Lewis acid    Lewis base    Complex

When aluminium is treated with dilute Naoh dihydrogen is evolved.
2Al(s) + 2NaOH(aq) + 6H₂O(l)\(\rightarrow\)2Na⁺[Al(OH)₄]^-(aq) + 3H₂(g)

\({ CaCO }_{ 3 }(aq)+{ CO }_{ 2 }+{ H }_{ 2 }O\longrightarrow Ca{ ({ HCO }_{ 3 }) }_{ 2 }\)
                                           Calcium bicarbonate (soluble)

\(CO+{ H }_{ 2 }\xrightarrow [ ZnO,{ Cr }_{ 2 }{ O }_{ 3 } ]{ 200 \ atm,\ 675K } { CH }_{ 3 }OH\)
                        methanol

When borax is heated strongly, a transparent glassy bead which consists of sodium metaborate and boric anhydride is formed.
Na₂B₄O₇.10H₂O\(\overset { heat}{ \rightarrow } \)Na₂B₄O₇ + 10H₂O
                                    Anhydrous (swollen white mass)
Na₂B₄O₇\(\overset { heat }{ \rightarrow } \)\(\underbrace { 2Na{ BO }_{ 2 }\quad \quad \quad \quad \quad \quad \quad \quad +\quad \quad \quad \quad \quad \quad \quad \quad \quad \quad \quad { B }_{ 2 }{ O }_{ 3 }\\ Sodium\quad metaborate \ Boric \ anhydride }_{ Transparent \ glassy \ bead } \)

The phenomenon of existence of an element in two or more forms which differ in physical properties but have almost same chemical nature is known as allotropy and the different forms of the element are known as allotropes.