Hydrogen And Its Compounds Question 210
Question: At its melting point ice is lighter than water because
Options:
A) $ H_2O $ molecules are more closely packed in solid state
B) Ice crystals have hollow hexagonal arrangement of $ H_2O $ molecules
C) On melting of ice the $ H_2O $ molecule shrinks in size
D) Ice forms mostly heavy water on first melting
Show Answer
Answer:
Correct Answer: B
Solution:
[b] in the structure of ice each molecule of $ H_2O $ is surrounded by three $ H_2O $ molecules in hexagonal honey comb manner. Whereas in water, each molecule is surrounded by four neighbouring molecules randomly which results in an open cage-like structure. As a result there are a number of -hole- or open spaces. In such a structure lesser number of molecules bonds are packed per ml. when ice melts a large number of hydrogen bonds are broken. The molecules therefore move into the holes or open spaces and come closer to each other than they were in solid state. This results in sharp increase in the density. Therefore ice has lower density than water.
BETA
