The statement  which is true  is
Fluorine  is more reactive  than nitrogen because fluorine  needs  only  one electron to fill  its  outermost  shell.
      <u><em>Explanation</em></u>
Fluorine  has  electron configuration  of 1S²2S²2P⁵  while nitrogen  has 1S²2S²2P³  electron configuration.
 The 2P sub shell  for nitrogen   is  half filled  therefore it is sable  than fluorine.
 since  p orbital  can hold a maximum  of  6  electrons ,Fluorine  requires  1 electron  to  completely fill  it's 2P  sub shell  which make it    more  reactive than nitrogen.
 
        
             
        
        
        
Answer:
All three are present
Explanation:
Addition of 6 M HCl would form precipitates of all the three cations, since the chlorides of these cations are insoluble:  .
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- Firstly, the solid produced is partially soluble in hot water. Remember that out of all the three solids, lead(II) choride is the most soluble. It would easily completely dissolve in hot water. This is how we separate it from the remaining precipitate. Therefore, we know that we have lead(II) cations present, as the two remaining chlorides are insoluble even at high temperatures.
- Secondly, addition of liquid ammonia would form a precipitate with silver: ![AgCl (s) + 2 NH_3 (aq) + H_2O (l)\rightarrow [Ag(NH_3)_2]OH (s) + HCl (aq)](https://tex.z-dn.net/?f=AgCl%20%28s%29%20%2B%202%20NH_3%20%28aq%29%20%2B%20H_2O%20%28l%29%5Crightarrow%20%5BAg%28NH_3%29_2%5DOH%20%28s%29%20%2B%20HCl%20%28aq%29) ; Silver hydroxide at higher temperatures decomposes into black silver oxide: ; Silver hydroxide at higher temperatures decomposes into black silver oxide:![2 [Ag(NH_3)_2]OH (s)\rightarrow Ag_2O (s) + H_2O (l) + 4 NH_3 (g)](https://tex.z-dn.net/?f=2%20%5BAg%28NH_3%29_2%5DOH%20%28s%29%5Crightarrow%20Ag_2O%20%28s%29%20%2B%20H_2O%20%28l%29%20%2B%204%20NH_3%20%28g%29) . .
- Thirdly, we also know we have  in the mixture, since addition of potassium chromate produces a yellow precipitate: in the mixture, since addition of potassium chromate produces a yellow precipitate: . The latter precipitate is yellow. . The latter precipitate is yellow.
 
        
             
        
        
        
Physical properties include: appearance, texture, color, boiling point, melting point, ect.