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One example of a physical change is: A-burning paper B-baking a cake C-heating table...

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safera | eNotes Newbie

Posted October 20, 2013 at 7:28 PM via web

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One example of a physical change is:

A-burning paper

B-baking a cake

C-heating table suger until it becomes carmelized

D-salt water

3 Answers | Add Yours

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ncchemist | eNotes Employee

Posted October 20, 2013 at 8:05 PM (Answer #1)

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In chemistry, when we talk about a change we are talking about one of two types of changes: physical and chemical.  A chemical change is a change whereby the actual chemical identity of the substance has changed.  In others words, chemical bonds are broken and remade to convert one type of molecule into another different molecule.  A physical change is a change in form only of a substance; the actual chemical identity is still the same.  A physical change represents a change in the physical properties of a substance, like the color, shape, size, density, crystal form, change of phase (solid, liquid, or gas), etc.  Let's look at each answer choice.

A.  Burning a piece of paper is technically called combustion.  It represents a chemical reaction whereby the carbon compounds in the paper are oxidized into different chemicals like carbon dioxide and water vapor.  This is a chemical change.

B.  Baking a cake changes the texture and consistency of the batter, but the chemical elements that went into the batter remain the same.  This is a physical change.

C.  Heating sugar until carmelization.  This again combusts the carbon in the sugar molecules to make new chemicals.  This is a chemical change.

D.  Salt water.  This is simply of solution of salt in water and represents neither a chemical or physical change.

So the correct answer is B.

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Yojana_Thapa | Student, Grade 10 | (Level 1) Valedictorian

Posted January 25, 2014 at 7:15 PM (Answer #2)

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Physical change:

B. Baking a cake

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parama9000 | Student, Grade 11 | (Level 1) Valedictorian

Posted January 30, 2014 at 7:34 AM (Answer #3)

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B- Baking a cake

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