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Harman [31]
4 years ago
12

Which of the following is an irreversible physical change?

Chemistry
1 answer:
Yuliya22 [10]4 years ago
3 0

Answer:

b) sharpening a pencil

Explanation:

If you melt lead, boil water, or dissolve sugar in water, you can return all of them back to their original state. If you sharpen a pencil, you can't reattach the shavings as they were originally.

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Heating up an object can cause it to
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Answer:

We know that kinetic energy is one of the forms of internal energy, so the release of heat from an object causes a decrease in the average kinetic energy of its particles.

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What is friction force ?
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A student is performing a titration to determine the concentration of a 20.0 mL sample of hydrochloric acid. What did the studen
irakobra [83]

Answer:

0.25M HCl

Explanation:

The reaction of HCl with NaOH is:

HCl + NaOH ⇄ H₂O + NaCl

<em>Where 1 mole of HCl reacts per mole of NaOH</em>

The end point was reached when the student added:

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As 1 mole of HCl reacted per mole of NaOH, moles of HCl present are:

<em>0.00500 moles HCl</em>

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It all adds up worksheet
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Atomic number and the number of protons are the same...
Neutrons = Mass number - number of protons
Electrons are same # unless there is a charge 
The whole number you see on the periodic table is the atomic number of the element which is also same as the number of protons

1) carbon - 14  ;  Mass number = 14 , Protons = 6 , Neutrons = 14 - 6 = 8 
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2) Lead - 208  ; Mass # = 208 , Protons = 82 , Neutrons = 208 - 82 = 126
                          Electrons = 82

3) Uranium - 239 ; Mass # = 239  , Protons  =  92,Neutrons = 239 - 92 = 147
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4) Uranium - 238  ; Mass # = 238 , Protons = 92 , Neutrons = 238 - 92 = 146
                                   
Electrons = 92 

5) Tin - 118  ; Mass # = 118 , Protons = 50 , Neutrons = 118 - 50 = 68
                         Electrons = 50
8 0
3 years ago
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