Ill say <span>calcium hydroxide but hope this helps :)</span>
        
             
        
        
        
Visual representation of covalent bonding indicating the valence shell electrons in the molecule, lines represents the shared pair of electron and pair of electrons that are not involved in bonding are represented as dots(lone pairs) are known as Lewis structures.
Compound formation takes place in order to complete the octet of each element that is according to octet rule, each atom forms bond with other atom in order to complete their octet that is to get eight electrons in its valence shell and attain stability.
An organic compound of the form 
 is known as ketene. 
The given ketene is 
.
The number of valence electron of:



The number of valence electrons in 
 = 
2 electrons are involved in each single bond between carbon and hydrogen and 4 electrons are involved in each double bond formed between carbon-carbon and carbon-oxygen. Hence, the total number of electrons involved in bond formation are 12 and rest 2 pair of electrons are present on oxygen as lone pair of electrons.
Therefore, the attached image is the Lewis structure of 
 .
 
        
             
        
        
        
She would observe a yellowish  solid precipitate which is the lead iodide and a white solid precipitate which is the  potassium nitrate.
This is because the lead nitrate solution which contains particles of lead will mix with the potassium iodide solution containing  particles of iodide. Upon mixing,the  lead particles  from the Lead nitrate solution combines with the  iodide particles from Potassium iodide and form two compounds, a yellowish solid precipitate called lead iodide and a white solid  precipitate called Potassium nitrate. 
The formation of entirely two new compounds is known as the double displacement reaction and can be written in a chemical equation as  
2KI(aq.)+Pb(NO₃)₂(aq.)------>2KNO₃(aq.)+PbI ₂(s)
See similar answer here  :https://brainly.in/question/46262462
 
        
                    
             
        
        
        
Answer:
Each carbon atom is covalently bonded to 4 other carbon atoms in diamond. A large amount of energy is required to split these atoms apart. This is because of the fact that covalent bonds are strong.
 
        
                    
             
        
        
        
Answer:
The third one
Explanation:
Nickel-62 has the highest binding energy per nucleon of any isotope for any element. Isotopes heavier than 62Ni cannot be formed by nuclear fusion without losing energy.