Question

Hydrogen and carbon dioxide are both _________, if they are formed in an experiment you will see ___________,this can be a sign of a chemical _______.In chemical changes, new substances or ____________ are produced. ​

Answer 1

• Melting and burning of candle wax is an example of both physical and chemical changes. Answer: ... When wood is burnt the moisture present in it turns to vapour ,it is a physical change while it burns and generate CO2 is a chemical change.
• There are five signs of a chemical change:
• Color Change.
• Production of an odor.
• Change of Temperature.
• Evolution of a gas (formation of bubbles)
• Precipitate (formation of a solid)
• Chemical changes occur when a substance combines with another to form a new substance, called chemical synthesis or, alternatively, chemical decomposition into two or more different substances. These processes are called chemical reactions and, in general, are not reversible except by further chemical reactions.
• A chemical change is a permanent change. A Physical change affects only physical properties i.e. shape, size, etc. ... Some examples of physical change are freezing of water, melting of wax, boiling of water, etc. A few examples of chemical change are digestion of food, burning of coal, rusting, etc.

Answer 2

Explanation:

Hydrogen and carbon dioxide are both ____gas_____, if they are formed in an experiment you will see ______bubble_____,this can be a sign of a chemical ____reaction___.In chemical changes, new substances or _____new and different physical and chemical properties_______ are produced

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