When $MnO_2$ is fused with $KOH$,a coloured compound is formed. The product and its colour are:

Which alloy is used for making coins?

Which from the following alloys is used in gas turbine engines?

The conversion of pig iron to steel frequently requires the addition of
$(I)$ oxygen or iron oxide
$(II)$ transition elements
$(III)$ inner transition elements
$(IV)$ silica

$X + KOH + O_2 \to Y + H_2O$,
$Y + H_2SO_4 \to Z + K_2SO_4 + MnO_2 + H_2O$
Identify $X, Y$ and $Z$ in the above reactions.

Which of the following melts in boiling water?