Answer: 20.7 kJ
Explanation:
According to first law of thermodynamics:
=Change in internal energy
q = heat absorbed or released
w = work done or by the system
w = work done on the system=
  {Work is done on the system is positive as the final volume is lesser than initial volume}
w = 4.51 kcal = 
    (1kcal = 4.184kJ) 
q = +1.79 kJ   {Heat absorbed by the system is positive}

Thus 
 for a system that receives 1.79 kJ of heat from surroundings and has 4.51 kcal of work done on it at the same time is 20.7 kJ
 
        
             
        
        
        
tell me what to do dudette
 
        
             
        
        
        
Answer:
The volume of water needed to recrystallize 0.700 g of benzoic acid is 10.29 mL.
Explanation:
For the complete recrystalization, 
the amount of hot water should be such that, the benzoic acid is completely soluble in it.
As we are given that the solubility of benzoic acid in hot water is 68.0 g/L. Now we have to determine the volume of water is needed to recrystallize 0.700 g of benzoic acid.
we conclude that,
As, 68.0 grams of benzoic acid soluble in 1 L of water.
So, 0.700 grams of benzoic acid soluble in  of water.
The volume of water needed = 0.01029 L = 10.29 mL
conversion used : (1 L = 1000 mL)
Therefore, the volume of water needed to recrystallize 0.700 g of benzoic acid is 10.29 mL.
 
        
             
        
        
        
Answer: Liquid has no definite shape but it has definite volume. The particles are free to move over each other but are still attracted to each other. Liquids can be compressed into gas. 
Hope this helps :)