Yes 5a is equal to 81 for fraction equally
        
             
        
        
        
Answer:279.1 K
Explanation:
You'll be using Gay-Lussac's Law for this. P1/T1=P2/T2
I have a class for this, and one of the practice questions was formatted this way, so I used that format and substituted said numbers as needed
P1:67 Pa
P2:60 Pa
T1:250 K
T2:?
I really hope this helps!
 
        
             
        
        
        
Answer: D) All of the above
Explanation: 
 The sources of errors in the kinetic experiment are depends upon the tools, due to some personal errors and also due to some methodological problem. As, experimental error during kinetic study is due to the difficulty to characterize the experimental errors depend on reaction conditions. The behavior of the experimental errors are depend on specific feature of the experiment systems. 
 
        
             
        
        
        
The level in the beaker will increase because the volumes of the spheres will also be added to the volume of the water. First, we must determine the volume of each sphere. For this, we will use:
density = mass / volume
We can check the density of both aluminum and iron in literature, and given the mass, we may obtain the volume. 
Aluminum:
Density = 2.70 g/ml
Mass = 20.4 g
Volume = 20.4 / 2.7 = 7.56 ml
Iron:
Density = 7.87 g/ml
Mass = 49.4 g
Volume = 49.4 / 7.87 = 6.28 ml
Now, we add these volumes to the volume of water present:
75.2 + 6.28 + 7.56 = 89.04
The new level will be 89.0 ml