Acidic solution, hence we can assume water and H+ where ever required Step 1 Sn + 2H20 -----> SnO2 + 4H+ + 4e- Step 2 HNO3 + H+ + e- ------> NO2 + H20 Step 3 (eliminating electrons) Sn + 4HNO3 ---------->SnO2 + 4NO2 + 2H2O Solution Acidic solution, hence we can assume water and H+ where ever required Step 1 Sn + 2H20 -----> SnO2 + 4H+ + 4e- Step 2 HNO3 + H+ + e- ------> NO2 + H20 Step 3 (eliminating electrons) Sn + 4HNO3 ---------->SnO2 + 4NO2 + 2H2O.