1.8x10^24 atoms is How many atoms are in 1.50 moles of fluorine gas
        
             
        
        
        
Answer:
b) sharpening a pencil
Explanation:
If you melt lead, boil water, or dissolve sugar in water, you can return all of them back to their original state. If you sharpen a pencil, you can't reattach the shavings as they were originally.
 
        
             
        
        
        
Answer: 40 grams
Explanation:
The quantity of Heat Energy (Q) required to heat a substance depends on its Mass (M), specific heat capacity (C) and change in temperature (Φ)
Thus, Q = MCΦ
Since Q = 93.4J
 M = ?
C = 0.129 J/g.C
Φ = 40.4°C - 22.3°C = 18.1°C
Then, Q = MCΦ
Make Mass, M the subject formula 
M = Q/CΦ
M = (93.4J) / (0.129 J/g.C x 18.1°C) 
M = 93.4J / 2.33J/g
M = 40 g
Thus, the mass of the lead is 40 grams
 
        
             
        
        
        
It is 31.75g of copper is contained in .50 mole of copper.