B
mass of solute - 4.0 g
mass of solution - 100g + 4.0g = 104g
4/104 = 0.03846
0.03846 • 100 = 3.8%
        
             
        
        
        
Answer:
I believe that it is the 2nd option.
Explanation:
My reasonings are because C4H10O has 7 isomers. In which 4 are alcohol and the other 3 are ether. 
The first option is ethers, specifically ethoxyethane.
The third option is ethers, specifically 1-methoxypropane.
The fourth option is an alcohol, specifically 1- butanol.
Therefore, leads us to the 2nd option that it is NOT an isomer of C4H10O
 
        
             
        
        
        
Answer: Option (A) is the correct answer.
Explanation:
A covalent bond is formed when there occurs sharing of electrons between atoms. 
For example, in hydrogen atom there is one electron in its orbit and in a chlorine atom there is 7 valence electron. So, in order to attain stability both hydrogen and chlorine share electrons when they come close to each other.
Whereas except hydrogen and chlorine rest of the given atoms will form ionic bond, that is, bond formed by transfer of electrons.
Thus, we can conclude that a pair of hydrogen and chlorine will form a covalent bond.
 
        
                    
             
        
        
        
The correct answer is D, they are reviewed by experts.
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