Greetings,
You can get Potassium Nitrate from stores selling Scientific Equipment and Chemicals for Schools or Industrial Chemical Suppliers, There are many such stores in your city. Looks like you are making Sugar and Potassium Nitrate Rockets
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Be sure to keep the Potassium Nitrate mixture free from moisture. Be careful while preparing the mixture
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All the best in Exploring Space and Model Rocketry
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