If the outer shell is filled, the atom is stable. Atoms with unfilled outer shells are unstable, and will usually form chemical bonds with other atoms to achieve stability. Example of an unstable atom with a single electron in its outer-most shell. ... In covalent bonds, atoms share electrons to achieve stability.
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The molarity of a solution if it tale 12.0 grams of Ca(No3)2 is calculated as below
molarity = moles/volume in liters
moles = mass/molar mass = 12.0 g/ 164 g/mol = 0.073 moles
molarity is therefore = 0.073/0.105 = 0.7 M
Mass of the water : 2.23 g
<h3>Furter explanation</h3>
Heat
Q = m.c.Δt
m= mass, g
c = heat capacity, for water : 4.18 J/g° C.
ΔT = temperature
Q= 140 J
Δt = 75 - 60 = 15
mass of the water :

Answer: I. The number of molecules is conserved.
III. Atoms are neither created nor destroyed
Explanation:
According to the law of conservation of mass, mass can neither be created nor be destroyed. Thus the mass of products formed must be equal to the mass of reactants taken.
In order to get the same mass on both sides, the atoms of each element must be balanced on both sides of the chemical equation.
For example: 
Thus in the reactants, there are 4 atoms of hydrogen , 2 atoms of oxygen and 2 atoms of sodium.Thus there will be 4 atoms of hydrogen, 2 atoms of oxygen and 2 atoms of sodium in the product as well.
Answer: Option (b) is the correct answer.
Explanation:
It is known that in a gas, molecules are away from each other due to more kinetic energy between its particles. As a result, there are more number of collisions between them.
So, when we apply pressure on a gas then its molecules come closer to each other. Due to which there occurs decrease in its volume.
Thus, we can conclude that to investigate the compressibility of a gas increase the pressure on it.