<span> 2 hydrogen atoms attached to an oxygen atom.</span>
        
                    
             
        
        
        
Answer:
1 I'm doing this in science class right now I got help yesturday on it! hope this helps
 
        
             
        
        
        
 Answer:
- NaClO₃ > KBr > KNO₃ > NaCl.
Explanation:
The attached file contains the graph with the solubility curves for the four substances, KNO₃, NaClO₃, KBr, NaCl.
To determine the solubility of each salt at a certain temperature, you read the temperature on the horizontal axis, labeled Temperature (ºC), and move upward up to intersecting the curve of the corresponding salt. Then, move horizontally up to insersceting the vertical axis, labeled Solubility (g/100g of H₂O), to read the solubility.
The higher the reading on the vertical axis, the higher the solubility.
The red vertical line that I added is at a temperature of 40ºC.
The number in blue indicate the order in which the solubility curves are intersected at that temperature:
- 4: NaCl: this is the lowest solubility
- 3: KNO₃: this is the second lowest solubility
- 2: KBr: this is the third lowest solubility
- 1: NaClO₃: this is the highest solubility.
Thus, the rank, from most soluble to least soluble is:
- NaClO₃ > KBr > KNO₃ > NaCl.
 
        
             
        
        
        
<span>
If mass remains the same while the volume of a substance increases, the
density of the substance will decrease. The increase in the volume is called expansion, while the decrease in the volume is called contraction. 
</span><span>The density measures how much matter (mass) there is in a given amount of space (volume).  So, if the mass stays the same and the volume increases then there is the same amount of mass ad before but in bigger volume so the density is decreased. </span>