Answer:
B.111
Explanation:
Atomic mass = number of protons(or atomic number) + number of neutrons
186 = 75 + number of neutrons
number of neutrons = 186 -75 = 111
 
        
             
        
        
        
Solution :
Molar mass of  is :
 is :
M = 6×12 + 6×1 g
M = 78 g
78 gram of  contains
 contains  molecules.
 molecules.
So, 89.5 gram of  contains :
 contains :

Now, from the formula we can see that one molecule of  contains 2 hydrogen atom . So, number of hydrogen atom are :
 contains 2 hydrogen atom . So, number of hydrogen atom are :

Hence, this is the required solution.
 
        
             
        
        
        
According to Grahams law the rate of effusion of a gas is inversely proportional to the square root of it's molecular weight. The rate of diffusion is the measure of rate at which two gases mix. From this law we can say that for the two gases carbon monoxide and carbon dioxide, the rate of effusion of carbon monoxide is greater than that of carbon dioxide, this is because carbon monoxide is lighter (28 g) compared to carbon dioxide (44 g). 
        
             
        
        
        
You can use P1V1/T1 = P2V2/T2 but since pressure is constant is becomes V1/T1=V2/T2
V1=0.5 L
T1=203 K
T2=273 K
V2=unknown
0.5L/203 = V2/273
V2= 0.67 L so C
Hope this helps :)
        
             
        
        
        
In late 18th century, people wore rubber soled shoes called plimsolls, but they weren't the best sneakers. Around 1892, a US company named Keds started sneakers with a canvas top and rubber soles. By 1917, these were mass produced.