For air at room temperature, the atmospheric pressure is 1.0 $$ \times $$ 10⁵ Nm^$$-$$2 and density of air is 1.2 kgm^$$-$$3. For a tube of length 1.0 m, closed at one end, the lowest frequency generated is 84 Hz. The value of $$\gamma$$ (ratio of two specific heats) for air is