Answer of this question is D
Atomic number.
The atomic number is what defines the element.
If you cut the cube and keep all the pieces you are causing only physical change
The Lewis Structure of HCN is shown below,
Number of Bonding Electrons: In HCN Hydrogen is bonded to Carbon through single bond and Nitrogen is bonded to Carbon through Triple Bond. Single bond is formed by two bonding electrons, while, triple bond is formed by six bonding electrons, Hence,
Number of Bonding Electrons = 8
Number of Non-Bonding Electrons:
In HCN there is only one lone pair of electron present on Nitrogen atom which is not taking part in bonding. Hence,
Number of Non-Bonding Electrons = 2
Result: Number of Bonding Electrons = 8 Number of Non-Bonding Electrons = 2