Answer:
Krypton
Explanation:
When Selenium forms an ion, it is trying to become krypton which is a noble gas. 
Selenium belongs to the oxygen group on the periodic table. In this group, the atoms prefers to gain two electrons to complete their octet. When selenium gains two electrons, its octet is complete. 
This will make the atom resemble krypton on the periodic table of elements. 
This structure which is an octet confers a special stability on the element. 
 
        
             
        
        
        
Answer:
K2Cr2O7
Explanation:
Solubility refers to the amount of substance that dissolves in a given mass or volume of solvent. There are several units of solubility applicable in different areas.
Solubility is dependent on temperature. The solubility curve is a graphical representation of the dependence of solubility on temperature for different chemical species.
If we study the solubility curve closely, we will see that K2Cr2O7 has the highest solubility at 100°C. This means that if the trends continue, this substance will also have the highest solubility at 120°C. 
 
        
                    
             
        
        
        
delta g must be negative in order for the reaction to be spontaneous bb ♡
 
        
                    
             
        
        
        
This is an incomplete question, here is a complete question.
Calculate the volume in milliliters of a 1.29 mol/L iron(II) bromide solution that contains 275 mmol of iron(II) bromide . Round your answer to significant 3 digits.
Answer  : The volume of iron(II) bromide solution is, 
Explanation : Given,
Concentration of iron(II) bromide = 1.29 mo/L
Moles of iron(II) bromide = 275 mmol = 0.275 mol
conversion used : 1 mmol = 0.001 mol
Now we have to calculate the volume of iron(II) bromide.

Now put all the given values in this formula, we get:

Thus, the volume of iron(II) bromide solution is, 
 
        
             
        
        
        
4.01 kg in grams :
4.01 x 1000 = 4010 g
Density = mass / volume
7.86 = 4010 / volume
Volume = 4010 / 7.86
Volume = 510.17 cm³ 
hope this helps!