If they are in the same row they have the same number of outer electrons on the same main shell also known as valence electrons
if they are in the same column they have the same number of valence electrons but on different main shells
Answer:
The IHD = 0
There is no unsaturation in the compound C4H9Cl
Explanation:
IHD = Index for Hydrogen Deficiency .It determines total number of unsaturation or Pi- bond present in the molecule.It is calculated using the formula:
For Molecule:

Here . C = carbon
H = Hydrogen
O = Oxygen
N = Nitrogen
X = Halogen
The IHD is calculated as :
...............(1)
For example :
C4H8O2
Here c = 4 , h = 8 , o = 2 .
n = x=0
Put the value in equation (1) and find IHD



IHD = 1
For C4H9Cl
c = 4 , h = 9 and x = 1
IHD for this molecule can be calculated as :



= 0
This means there is no unsaturation in the molecule.
Each bond is sigma bond and properly saturated.
Explanation:
The driving force behind plate tectonics is convection in the mantle. Hot material near the Earth's core rises, and colder mantle rock sinks.
Answer:
c) A solid has a definite shape
Explanation:
Only solids have definite shape. Liquids acquire the shape of the container and gases have molecules that move randomly .Gases turn into plasma when
heat energy is added to it.