Answer:
i am unique and have a specific number in the periodic table
 
        
             
        
        
        
Answer:
D. 1.2 cm
Explanation:
1st, determine the units. We see that our ruler is in cm.
This rules out A and C.
2nd, determine answer.
We see that the penny extends past 1 and ends at 0.2.
So, the total is 1.2 cm.
 
        
             
        
        
        
The mole fraction of pentane in the vapor is 0.291
Vapour pressure rises with temperature and is a measurement of a substance's propensity to transform into a gaseous or vapour state. The boiling point of a liquid is the temperature at which the pressure exerted by its surroundings equals the vapour pressure present at the liquid's surface. 
The number of moles of a particular component in the solution divided by the overall number of moles in the sample solution is known as the mole fraction.
Using the formula for vapour pressure,
vapour pressure =  °
° ×
 ×  +
 +  °
° ×
 × 
vapour pressure = 151 ×  

 + 425 ×
 + 425 × 
240 = 151 - 151 + 425
 + 425
240 - 151 = -  151 + 425
 + 425 
89 = 274 
 =
 = 
0.291 = 
Therefore,  the mole fraction of pentane in the vapor is 0.291
Learn more about vapour pressure here;
brainly.com/question/25699778
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