<span>4000 kilogram/cubic meter
http://www.calculator.net/density-calculator.html?cdensity=&cdensityunit=kilogram%2Fcubic+meter&cvol...
</span>
A) <span>Particles need to collide in order to react</span>
Answer : The enthalpy change for the solution is 166.34 kJ/mol
Explanation :
First we have to calculate the enthalpy change of the reaction.
Formula used :

where,
= change in enthalpy = ?
C = heat capacity of water = 
m = total mass of sample = 2.174 + 127.4 = 129.6 g
= initial temperature = 
= final temperature = 
Now put all the given values in the above expression, we get:


Now we have to calculate the moles of AX added to water.

Now we have to calculate the enthalpy change for the solution.
As, 0.04592 moles releases heat = 7638.36 J
So, 1 moles releases heat = 
Therefore, the enthalpy change for the solution is 166.34 kJ/mol
Answer:
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The correct answer is C because diffusion is the movement of molecules from an area of higher concentration to an area of lower concentration.
HOPE THIS HELPS!
HAVE A GR8 DAY ;-)