Answer: Option D) covalent bonds between water molecules
In water, hydrogen bonds are best described as covalent bonds between water molecules
Explanation:
The hydrogen bonds between water molecules are covalent bonds because they are formed when oxygen attract the lone electron in hydrogen, thus resulting in the formation of a partially negative charge on the oxygen atom and a partially positive charge on two hydrogen atoms
Thus, the sharing of electrons between oxygen and hydrogen atoms is responsible for the covalent bonds between water molecules
Answer: The initial temperature of the iron was 
Explanation:

As we know that,

.................(1)
where,
q = heat absorbed or released
= mass of iron = 360 g
= mass of water = 750 g
= final temperature = 
= temperature of iron = ?
= temperature of water = 
= specific heat of iron = 
= 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 
Answer:
4725.6 g of (NH4)2SO4
Explanation:
Molar mass of a substance is the number of mass of the substance contained in one mole of the substance. It is also called the formula weight of the compound. The formula mass of (NH4)2SO4 is 132 g/mol Hence;
Now we know that;
1 mole of (NH4)2SO4 contains 132 g of (NH4)2SO4
35.8 moles of (NH4)2SO4 contains 35.8 * 132/1
= 4725.6 g of (NH4)2SO4