Identify the correct statements from the following.

A. In photosynthesis reaction, water is oxidised to oxygen.

B. An example for interstitial hydride is $\mathrm{MgH}_2$.

C. Sodium hexametaphosphate is used in the removal of permanent hardness of water.

Consider the following statements about group 13 elements.

A. $\mathrm{AlCl}_3$ gets stability by forming a dimer.

B. $\mathrm{BCl}_3$ is an electron deficient molecule.

C. $E_{M^{3+} / M}^{\circ}(\mathrm{V})$ is +1.26 for aluminium.

D. In +1 oxidation state thallium is unstable.

The incorrect statements are

What is the correct order of melting temperature of $\mathrm{C}, \mathrm{Si}, \mathrm{Ge}$ ?

Which one of the following statements is correct?