Which metal oxide is used to make blue glass?

$K_2Cr_2O_7$ on heating with aqueous $NaOH$ gives:

When a mixture of manganese dioxide,potassium hydroxide and potassium chlorate is fused,the product obtained is

Iodine is formed when potassium iodide reacts with a solution of

$NaCl + K_2Cr_2O_7 + \text{conc. } H_2SO_4$ $\xrightarrow{\Delta} P(\text{gas})$ $\xrightarrow{NaOH} Q$ $\xrightarrow[Pb(CH_3COO)_2]{CH_3COOH} R(\text{ppt})$
Which of the following is the correct statement?

Identify the incorrect statement.