A bond is non polar if it is between same atoms and polar if it is between different atoms.
Same atoms are like two dogs of same strength pulling a bone towards towards each other. But when it’s different atoms it’s like a big dog and small dog then the bone is more towards bigger dog. So it’s the same way in bonds.
Bonds are made up of electrons, when the more stronger pulling atom is present than other the electrons are more towards it and as a result we have polar bond. There is development of a kind of a negative pole and a positive pole.
The stronger atom has electrons towards itself so it has a little more negative charge while the other atom has positive charge. This makes bond polar.
So just look for bond between two different atoms, it would be polar.
Look at the pic below to see the answer.
Marked with green is bond between same atoms... one carbon and another carbon so it is not polar and test marked with blue are polar.
Well the answer should have been 10 but since the bonds at 3 and 8 are two of same type we count only one of them.
The answer is 8... well the answer should be 10 otherwise... discuss it with ur teacher
Answer: The mass of the sample will be 1417.7 grams.
Explanation:
We are given:

This means that 1 mole of NaCl has an enthalpy of fusion of 30.2 kJ
1 mole of NaCl has a mass of 58.44 grams.
So, 30.2 kJ of heat is require for a mass 58.44 grams of NaCl
So, 732.6 kJ of heat will be required for =
= 1417.65 grams of NaCl.
Hence, the mass of NaCl sample will be 1417.7 grams.
I believe the correct answer from the choices listed above is option A. Fan blades would be an analogy for electron cloud model. Austrian physicist Erwin Schrödinger (1887-1961) developed an “Electron Cloud Model<span>” in 1926. It consisted of a dense nucleus surrounded by a cloud of electrons. Hope this helps.</span>
It’s because new discoveries are made all the time sometimes what was considered right may be found out to be wrong