Informal vs. Formal Assessments. In order to properly understand what informal assessments are, we should first differentiate them from formal assessments. Formal assessments are designed to tell how well a student has progressed as evaluated against other students.
Rusting of iron consists of the formation of hydrated oxide, Fe(OH) 3, FeO(OH), or even Fe 2 O 3 .H 2 O. It is an electrochemical process which requires the presence of water, oxygen and an electrolyte. In the absence of any one of these rusting does not occur to any significant extent.
Oxidized metal gears. A paste of baking soda and water can remove rust from metal. Water molecules can penetrate the tiny openings in exposed metal. A dehumidifier may be used to reduce the chances of rust formation. Rust, also known as iron oxide, happens when iron or an iron alloy is exposed to oxygen and moisture.