Joseph Priestley devised an experiment to find out that water alone was the cause of the increase in the weight of the plant.

False

Jan Baptist van Helmont devised an experiment to find out that water alone was the cause of the increase in the weight of the plant.

He weighed the dry soil, then he weighed the small sapling and placed in the pot allowing only air and light and he regularly watered the plant. When sapling grows into a small tree again he weighed the plant. He found in increase of weight of the plant. He dried the soil in the pot in which sapling grew and took the weight of dried soil. He found very less difference in the weight of the soil before planting the sapling and after sapling grew into a small plant. So he came into conclusion that water was the cause of increase in weight of the plant.