When 8.53 g of sodium nitrate were heated in an open test tube, the mass of oxygen gas produced was 0.83g. Given the equation of the reaction as 2NaNO_3(s) rightarrow 2NaNO_2 (s) + O_2(g) Calculate the percentage of sodium nitrate that was converted to sodium nitrite. (Na =23.0 ;N =14.0 ;O = 16.0) (KCSE 2016 paper 1 question 7)