Answer:
Pure substance: sugar
A chemical change: occurs when methane is burned.
Explanation:
Pure substances have definite <em>constant compositions</em> (reflected in formulas) and have their own <em>chemical properties</em>. On the other hand, mixtures are made of two or more pure substances (<em>variable composition</em>) and their chemical properties depend on each combination. From the list, only sugar is a pure substance (C₁₂H₂₂O₁₁), whereas seawater, air, lemonade, and milk are mixtures.
Chemical changes (chemical reactions) occur when pure substances transform into others, and therefore there are new formulas. Conversely, in physical changes, pure substances <em>preserve their identity</em> (formula) but have changes in their <em>physical properties</em>. Methane being burned is a chemical change since new substances are formed:
CH₄ + O₂ ⇄ CO₂ + H₂O
Water vaporization, paper shredding and dissolution of solids in liquids are examples of physical changes.
Answer:
nickel is the correct answer
Beta radiation - negative charge and the mass of an electron
Gamma radiation- no mass and no charge
Alpha radiation- He 4+/2
