Bond line formula of HOCH(CN)$$_2$$ is :

The quantity which changes with temperature is :

The molecular formula of second homologue in the homologous series of mono carboxylic acids is

1 mole of $$\mathrm{PbS}$$ is oxidised by "$$\mathrm{X}$$" moles of $$\mathrm{O}_3$$ to get "$$\mathrm{Y}$$" moles of $$\mathrm{O}_2$$. $$\mathrm{X}+\mathrm{Y}=$$ _________.