Answer : The correct option is C.
Explanation :
Chemical change : It is defined as a change in which a new compounds are formed by the chemical reaction. Changes occurs in their chemical composition and properties.
The molecular structure of a substance changes in a chemical reaction is a chemical change.
- Change in molecular structure means that there is a breaking and formation of bonds in a molecule.
The example of chemical change in terms of change in molecular structure is the reaction of hydrogen with oxygen.
The reaction of hydrogen with oxygen is,

In this reaction, the H-H bond is break and O-H bond is form.
Answer:
A hypothesis is a possible explanation for a set of observations or an answer to a scientific question. A hypothesis must be testable and measurable.
Explanation:
A rock is definitely more dense. If you were to put a cloud in water it would float/stay above it and a rock would sink to the bottom
Answer :
Example of polar covalent molecules H-O-H(water), ammonia
Explanation:
The presence of intermolecular Hydrogen bonding makes the boiling point of water unexpectedly high, and the polar covalent nature makes it dissolve polar solute/compound