Sodium is heated in air at $300 ^{\circ}C$ to form x.x absorbs $CO_2$ and forms $Na_2CO_3$ and Y. Which of the following is Y?

Question

$$\begin {array} {1 1} (a)\;H_2 & \quad (b)\;O_2 \\ (c)\;H_2O_2 & \quad (d)\;O_3 \end {array}$$