Roots obtain oxygen from air in the soil for respiration. In the absence or deficiency of `O_2` root growth is restricted or completely stopped . How do the plants growing in marshlands or swamps obtain their `O_2` required for root respiration?

What volume of air at 1 atm and 273K containing 21% of oxygen by volume is required to completely burn sulphur (S_8) present in 200g of sample , which contains 20% inert material which does not burn. Sulphur burns according to the reaction 1/8 S_8(s)+O_2(g)rarrSO_2(g)

Oleum is considered as a solution of SO_(3) in H_(2)SO_(4) , which is obtained by passing SO_(3) in solution of H_(2)SO_(4) When 100 g sample of oleum is diluted with desired mass of H_(2)O then the total mass of H_(2)SO_(4) obtained after dilution is known is known as % labelling in oleum. For example, a oleum bottle labelled as ' 019% H_(2)SO_(4) ' means the 109 g total mass of pure H_(2)SO_(4) will be formed when 100 g of oleum is diluted by 9 g of H_(2)O which combines with all the free SO_(3) present in oleum to form H_(2)SO_(4) as SO_(3)+H_(2)O to H_(2)SO_(4) 1 g of oleum sample is diluted with water. The solution required 54 mL of 0.4 N NaOH for complete neutralization. The % free SO_(3) in the sample is :

Phospheric acid (H_(3)PO_(4)) perpared in two step process . (1) P_(4)+5O_(2) to P_(4)O_(10)" "(2) P_(4)O_(10) + 6H_(2)O to 4H_(3)PO_(4) Well allow 62 g of phosphrous to react with exces oxygen which from P_(4)O_(10) in 85% yield . In the sep (2) reaction 90% yield of H_3)PO_(4) is obtained . Mass of H_(3) PO_(4) produced is :