Question: what is the minimum distance between a node and antinode produced in a stationary wave?
Answer: Nodes and anti-nodes are formed in stationary waves. In a stationary wave, the distance between two successive nodes(anti-nodes) is one half wavelength. Therefore​, the distance between a node and the immediate next anti-node is one fourth of a wavelength. Therefore the wavelength of the wave = 5 cm * 4 = 20 cm.