The weight percentage of oxygen in $NaOH$ is _______.

 

The atomic mass of Sodium (Na) is 23, Oxygen (O) is 16 and Hydrogen (H) is 1.

Total mass of the compound = $23+16+1=40$

Weight percentage $=\frac{\mathrm{Atomic} \mathrm{mass} \mathrm{of} \mathrm{atom}}{\mathrm{Total} \mathrm{mass} \mathrm{of} \mathrm{thecompound}}$

So, weight percentage of Oxygen = $\frac{16}{40}=40\%$

Therefore, the weight percentage of oxygen in $\mathrm{NaOH}$ is 40%.