Dehydration of oxalic acid with concentrated $H_2SO_4$ produces ............

Fire extinguishers contain $H_2SO_4$ and which one of the following?

In the following reaction,assign the state for the underlined atom in the product of complete hydrolysis at $R.T.$:
$\underline{B}_2H_6 + H_2O \longrightarrow H_3BO_3 + H_2 \uparrow$

Identify the catalyst used in the following reaction: $CO_{(g)} + H_2O_{(g)} \xrightarrow{623 \ K} CO_{2_{(g)}} + H_{2_{(g)}}$

Semi-water gas is a mixture of which of the following?

When sugar is brought into contact with concentrated $H_2SO_4$,it turns black due to .......