The answer is D. Proteins. I know because I tried C. and I got it wrong. It was my last attempt on the quiz, and since I got it wrong they showed me the answer. (i like ur prp btw) 
        
                    
             
        
        
        
Answer:
Covalent bond is a type of bond involves the bonding of two ions of opposite charges.
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<u>PLEASE</u><u> MARK</u><u> ME</u><u> BRAINLIEST</u><u>.</u></h3>
 
        
             
        
        
        
Answer: The initial temperature of the iron was 
Explanation:

As we know that,  

![m_1\times c_1\times (T_{final}-T_1)=-[m_2\times c_2\times (T_{final}-T_2)]](https://tex.z-dn.net/?f=m_1%5Ctimes%20c_1%5Ctimes%20%28T_%7Bfinal%7D-T_1%29%3D-%5Bm_2%5Ctimes%20c_2%5Ctimes%20%28T_%7Bfinal%7D-T_2%29%5D) .................(1)
         .................(1)
where,
q = heat absorbed or released
 = mass of iron = 360 g
 = mass of iron = 360 g
 = mass of water = 750 g
 = mass of water = 750 g
 = final temperature =
 = final temperature = 
 = temperature of iron = ?
 = temperature of iron = ?
 = temperature of water =
 = temperature of water = 
 = specific heat of iron =
 = specific heat of iron = 
 = specific heat of water=
 = specific heat of water= 
Now put all the given values in equation (1), we get
![-360\times 0.450\times (46.7-x)=[750\times 4.184\times (46.7-22.5)]](https://tex.z-dn.net/?f=-360%5Ctimes%200.450%5Ctimes%20%2846.7-x%29%3D%5B750%5Ctimes%204.184%5Ctimes%20%2846.7-22.5%29%5D)

Therefore, the initial temperature of the iron was 
 
        
             
        
        
        
That answer is true. bleh bleh bleh bleh