Heat require to boil 15.6 g iron from 122 C0to 355 C0 whereas,

Where, m is mass of iron
s is specific heat of iron
d T is change in temperature in celcius

If
1 cal = 4.2 J
Then,

Thus 0.389 k cal of enrgy is required by a 15.6 g Fe to reach to 355 C^0
Answer:
Hydrogen bonds are totally different to both covalent bonds and ionic bonds. Hydrogen bonds are intermolecular bonds, that means they occur in between two molecules. ... When H atom is close to O,F, N atoms those atoms can attract H atoms electrons temporarily, thus making a weak bond.
Explanation:
N<span>etwork of bonded ions is established</span> between two atoms due to transfer of electrons from one atom to the other.
therefore,
Sodium chloride is formed from a network of bonded ions.
hence the right answer is <span>D) salt, NaCl</span>