The ionizing power and the penetration range of radioactive radiations increase in the order:

Out of the three radioactive radiations, the $\alpha$-rays are the most ionizing but least penetrative while the $\gamma$-rays are the least ionizing but most penetrative:

(i) α,β and γ radiations are arranged in the ascending order with respect to their penetrating power as:α < β < γ.
(ii) α,β and γ radiations are arranged in the ascending order with respect to their ionizing power as:γ < β < α.