ช่วยด้วยค่าาาาาาาา ด่วนมากๆๆๆๆ

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        <center><a href="#pagetwo" data-transition="pop" class="ui-btn ui-btn-inline">LET 'S START</a></center>
        
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            <a href="#pagethree" class="ui-btn ui-icon-carat-r ui-btn-icon-left">ปฏิกิริยา Redox</a><br />
            <a href="#pagefour" class="ui-btn ui-icon-carat-r ui-btn-icon-left">ปฏิกิริยา กรด-เบส</a><br />
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        <br /><br />
        <label>
		<select id="D1" name="D1" >
		    <option value="">--สารที่1--</option>
            <option value="1" id="1">Fe2+ (ใส)</option>
            <option value="2" id="2">Cr2O2-7 (สีส้ม)</option>
            </select></label>
        
        <label>
        <select id="D2" name="D2" >
		    <option value="">--สารที่2--</option>
             <option value="1" id="1">Fe2+ (ใส)</option>
            <option value="2" id="2">Cr2O2-7 (สีส้ม)</option>
            </select></label>
        
            
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           <br><center>
            <table width=90% ><tr><td style="border:3px dashed black;" bgcolor="CCFFFF">
            <br><p><b>ปฏิกิริยาออกซิเดชัน</b> 
            <center>6Fe<sup>2+</sup>  ->  6Fe<sup>3+</sup>  +  6e<sup>-</sup></center>
               
            
            <br><p><b>ปฏิกิริยารีดักชัน</b></p>
            <center>Cr<sub>2</sub>O<sup>2-</sup><sub>7</sub> + 6e<sup>-</sup> + 14H<sup>+</sup>  ->  2Cr<sup>3+</sup> + 7H<sub>2</sub>O</center>
            
            <br><p><b>ปฏิกิริยารวม</b></p>
            <center>6Fe<sup>2+</sup> + Cr<sub>2</sub>O<sup>2-</sup><sub>7</sub> + 14H<sup>+</sup>  ->  6Fe<sup>3+</sup>+ 2Cr<sup>3+</sup> + 7H<sub>2</sub>O</center> </td></tr></table></center>
         
            
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        <!--------------------------------------------จบ redox 1 ---------------------------------------------------->
            
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        <!----------------------------------------------จบ redox 2 ---------------------------------------------->    
     
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                    <img src = "img/2.png" weidth="220" height="220">
                    <img src = "img/3.png" weidth="220" height="220"></center>
            
            <label>
		<select id="D3" name="D3" >
		    <option value="">--สารที่1--</option>
            <option value="3" id="3">HCl (กรดไฮโดรคลอริก)</option>
            <option value="4" id="4">NaOH (โซเดียมไฮดรอกไซด์)</option>
            </select>
            </label>
        <label>
        <select id="D4" name="D4" >
		    <option value="">--สารที่2--</option>
            <option value="5" id="5">Bromthymol blue (pH = 6.0-7.6)</option>
            <option value="6" id="6">Phenol Red (pH = 6.0-7.6)</option>
            </select>
            </label>
        <label>
        <select id="D5" name="D5" >
		    <option value="">--สารที่3--</option>
            <option value="7" id="7">HCl (กรดไฮโดรคลอริก)</option>
            <option value="8" id="8">NaOH (โซเดียมไฮดรอกไซด์)</option>
            </select>
            </label>
        
  
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     <!----------------------------------------------จบ ph1 ------------------------------------------------------->           
    
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    <!---------------------------------------------จบ ph3 ---------------------------------------------------------->            
    
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   <!--------------------------------------------จบ ph4 ------------------------------------------------------------->             
    
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    <!--------------------------------------------- จบ ph5 --------------------------------------------------------->            
    
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    <!---------------------------------------------------จบ ph6 ---------------------------------------------------->            
   
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   <!-------------------------------------------------จบ ph7 --------------------------------------------------------->             
    
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  <!------------------------------------------------จบ ph8 ---------------------------------------------------------->              
    
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            <center><img src = "img/cheng.png" width="50%" height="50%"></center>
       
        
        <div data-role="main" class="ui-content">
        
            <center><img src = "img/3.png" width="210" height="210">
                    <img src = "img/2.png" width="210" height="210">
                    <img src = "img/1.png" width="210" height="210"></center>
            <label>
		<select id="D6" name="D6" >
		    <option value="">--สารที่1--</option>
            <option value="6" id="6">CoCl4</option>
            <option value="7" id="7">HCl</option>
                </select></label>
      
            
        <label>    
        <select id="D7" name="D7" >
		    <option value="">--สารที่2--</option>
            <option value="8" id="8">H2O (น้ำเปล่า)</option>
            </select></label>
            
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   <!---------------------------------------------------จบ pagefive ------------------------------------------->         
            
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        <source src="video/c1.mp4" type="video/mp4">
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            <br>
            <label>
        <select id="D8" name="D8" >
		    <option value="">--เลือกสารเพิ่ม--</option>
            <option value="9" id="9">CoCl4</option>
            <option value="10" id="10">HCl</option>
            <option value="11" id="11">H2O (น้ำเปล่า)</option>
		  </select></label>
            <br><br>
           <div class="ui-grid-a">
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   <!---------------------------------------------จบ c1 ------------------------------------------------------------>             
    
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         <center><img src = "img/cheng.png" width="50%" height="50%"></center>
        
        <div data-role="main" class="ui-content">
        
            <center><video width="50%" height="50%" controls>
        <source src="video/c2.mp4" type="video/mp4">
</video></center>
            
            <br>
            <label>
        <select id="D9" name="D9" >
		    <option value="">--เลือกสารเพิ่ม--</option>
            <option value="12" id="12">CoCl4</option>
            <option value="13" id="13">HCl</option>
            <option value="14" id="14">H2O (น้ำเปล่า)</option>
            </select></label>
            <br><br>
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    <!--------------------------------------------------จบ c2 ------------------------------------------------------->        
    
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    <!----------------------------------------------จบ c3 ------------------------------------------------------------->       
    
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   <!-------------------------------------------------จบ c4 --------------------------------------------------------->
        
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   <!----------------------------------------------------จบ c5------------------------------------------------------->         
            
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  <!--------------------------------------------------จบ c6 ------------------------------------------------------->          
            
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  <!----------------------------------------------------จบ c7 --------------------------------------------------->          
            
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   <!--------------------------------------------------จบ c8 --------------------------------------------------->         
    
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