Voltage supply is given as $$V  =10 sin (1000t) $$ Comparing it with  $$V = V_o  sin wt$$ We get  $$w = 1000$$ Inductance of coil is given as  $$L = 20 mH = 20 imes 10^{-3} H$$ Thus inductive reactance of coil  $$X_L = wL$$ $$implies X_L = 1000 imes 20 imes 10^{-3} = 20 Omega$$