Answer:
A. since Nitrogen has 7 electrons and when it gains 3 electrons it will have 10 electrons. using short hand rule it is [Ne]
Answer : The molal freezing point depression constant of liquid X is, 
Explanation : Given,
Mass of urea (solute) = 5.90 g
Mass of liquid X (solvent) = 450 g = 0.450 kg
Molar mass of urea = 60 g/mole
Formula used :

where,
= change in freezing point
= freezing point of solution = 
= freezing point of liquid X = 
i = Van't Hoff factor = 1 (for non-electrolyte)
= Molal-freezing-point-depression constant = ?
m = molality
Now put all the given values in this formula, we get


Therefore, the molal freezing point depression constant of liquid X is, 
Metallic solids or metallic structures experience metallic bonds which are the forces of attractions between the sea of electrons and the nucleus of the metallic atoms. They share a network of highly delocalized electrons.
I therefore think that the packing efficiency decreases as the number of nearest neighbors decreases.
Answer:
In organic chemistry, the structural formula shows the bonding and general layout of the molecule.
Explanation:
It can also help in naming the molecule, as many compounds with the same molecular formula have different structural formulas, for example cycloalkanes and alkenes, or aldehydes and ketones.
It tells us about the constituents of the compound, or in other words, the functional groups present. This enables us to predict what kind of properties the compound has and what kind of reactions it can undergo.
It can also help us determine the stereochemistry (shape and spatial orientation) of the compound. This is especially important in organic chemistry and organic chemstry, since certain important reactions will proceed if and only if a molecule with the right shape is employed.
It is called Mass.
Among the physical characteristics of a matter which includes Weight, Mass, Volume, and Density the only characteristic that does not change is the mass. The mass of an object never change from place to place. All the objects have a mass and that is why there is a weight but it changes depends on the gravity. Mass don't.