Question

1.    Why does ice float when placed in water?
What roles do hydrogen bonding plan in this phenomena?

2.    What information does the octane rating of a fuel provide?
When is a fuel with a high octane rating necessary?

Answer 1

Q.1 :

Water has unique character in its density. In its solid phase, there is specific arrangement of water creates space between them. This specific structure is known as cage structure. This empty space in solid makes its density lower than liquid phase of water. So when ice is placed in water it floats unexpectedly.

The hydrogen bonding:

Hydrogen bonding is the intermolecular forces present in hydrogen atom bonded to the electronegative atom mainly N , O and F and the electronegative atoms. Water molecules are in solid phase so are attracted due this type of forces make themselves in such a way that there is a formation cage structure.

If such H-bonding is not present in water then it would have been have the same character like other substance. So the H bonding has much more important role it.

One of its most important advantage to planate is saving aquatic life. In the see ice float and aquatic life is saved because of it.

Q. 2 :

Octane number tells about performance of engine. High octane number fuel performs good than the one that has lower.

Especially in case of diesel engine high octane rating is necessary. Since its role there is to withstand at the compression condition.