Tính nồng độ phần trăm của dung dịch NH4OH 15M, biết rằng khối lượng riêng là 0.899 g/ml, khối lượng mol phân tử là 17.03.

Large helium-filled balloons are used to lift scientific equipment to high altitudes. what is the pressure inside such a balloon if it starts out at sea level with a temperature of 10.0ºc and rises to an altitude where its volume is twenty times the original volume and its temperature is – 50.0ºc ?

Chemical bonds result from the interaction of the from two or more atoms. a. protons b. electrons c. neutrons d. nuclei

Food can lose electrons to air. this loss of electrons can create free radicals that destroy chemical bonds, hence spoiling the food. which term describes this process?