A definite volume of pure ammonia $\left({\mathrm{NH}}_3\right)$ gas is passed through a series of electric sparks by which the volume becomes 90 ml. The increase in volume is due to formation of nitrogen $\left({\mathrm{N}}_2\right)$ and hydrogen $\left({\mathrm{H}}_2\right)$ gases. All the gases finally present are washed with dilute sulphuric acid solution, by which the volume of gases becomes 80 ml. All the volumes are measured at the same temperatures and pressure Which of the following statement(s) is/are correct regarding the original ammonia sample?

The volume of ${\mathrm{NH}}_3$ gas taken was 40 ml.