The same number of valence electrons exists in the same family of elements in the periodic table. In finding the answer to this problem, we just have to find the pair that belongs to the same family in the periodic table. The same family means same column. Among these, Oxygen and lead (Pb) are in the same family. This pair is the answer.
        
             
        
        
        
To calculate this, we need the Molarity formula. This formula tell us that Molarity, which is a concentration unit, is equal to the number of moles divided by the volume. In this question we already have the Molarity and the Volume, so let's build our equation:
C = n/V (You can see Molarity with the letter "C" because it means concentration)
3 = n/1
n = 1 * 3
n = 3 moles of NaOH
 
        
             
        
        
        
Answer:
 your answer is 12 hope it's correct answer
 
        
             
        
        
        
Answer:
Land resources such as gravel and bedrock are used to construct buildings, roads, and sidewalks. Land is also where city structures—such as buildings, roads, and sidewalks—are constructed. People use land resources such as bedrock and aggregate to construct buildings, roads, and sidewalks.
I hope this answer helps 
 
        
                    
             
        
        
        
Answer:
30 kJ
Explanation:
Arrhenius equation is given by:

Here, k is rate constant, A is Pre-exponential factor, Ea is activation energy and T is temperature.
taking natural log of both side
ln k = ln A - Ea/RT
In Arrhenius equation, A, R and T are constant.
Therefore,

 is the  lowering in activation energy by enzyme,
 is the  lowering in activation energy by enzyme,
R = 8.314 J/mol.K
T = 37°C + 273.15 = 310 K

