It is a statement of fact. explains how energy is produced, and describes the behavior of energy.
Answer:
Na₂CO₃.2H₂O
Explanation:
For the hydrated compound, let us denote is by Na₂CO₃.xH₂O
The unknown is the value of x which is the amount of water of crystallisation.
Given values:
Starting mass of hydrate i.e Na₂CO₃.xH₂O = 4.31g
Mass after heating (Na₂CO₃) = 3.22g
Mass of the water of crystallisation = (4.31-3.22)g = 1.09g
To determine the integer x, we find the number of moles of the anhydrous Na₂CO₃ and that of the water of crystallisation:
Number of moles = 
Molar mass of Na₂CO₃ =[(23x2) + 12 + (16x3)] = 106gmol⁻¹
Molar mass of H₂O = [(1x2) + (16)] = 18gmol⁻¹
Number of moles of Na₂CO₃ = 
= 0.03mole
Number of moles of H₂O = 
= 0.06mole
From the obtained number of moles:
Na₂CO₃ H₂O
0.03 0.06
Simplest
Ratio 0.03/0.03 0.03/0.06
1 2
Therefore, x = 2
Answer : Option B) All collisions between particles are perfectly elastic.
Explanation : Gases consits of molecules which are compressible because the gas particles which have a small volume compared to the container.
The collisions are perfectly elastic because when gases are left alone in a container they don't seem to lose energy and do not spontaneously get converted into a liquid, also energy is not lost during collisions.
In the diagram given above one can interpret that the gaseous molecules are in random motion inside the container and when they collide with other molecule of gas they do not lose energy. Therefore, this shows perfectly elastic collisions.
Given :
Chlorine's 3p sub level has 5 electrons in it.
To Find :
How many electron(s) more in the 3p sub-level to make it stable.
Solution :
Electronic configuration of Chlorine is :
[Ne] 3s² 3p⁵.
We know, p-orbit is stable with 6 electronic.
Therefore, to stable p-orbit 1 more electron is required in 3p sub-level.
Hence, this is the required solution.
