Explanation:
option option B is the correct answer of given statement helium-4(He)=2
When you say mhello les do uou mean moecules
Answer : The correct option is, (B)
Explanation :
Balance equation : Balanced equation are those equation in which the number of atoms of each element and the total charge must be same on products side and reactants side.
In the given options, only option (B) equation has correct formula and also a balanced equation.

while the other options has incorrect formulas and also an unbalanced equations.
The correct equation for option A is, 
The correct equation for option C is, 
The correct equation for option D is, 
Hence, the correct answer is, (B) 
We need to know the relationship between atmospheric pressure and the density of gas particles in an area of increasing pressure.
The relationship is: As air pressure in an area increases, the density of the gas particles in that area increases.
For any gaseous substance, density of gas is directly proportional to pressure of gas.
This can be explained from idial gas edquation:
PV=nRT
PV=
RT [where, w= mass of substance, M=molar mass of substance]
PM=
RT
PM=dRT [where, d=density of thesubstance]
So, for a particular gaseous substance (whose molar mass is known), at particular temperature, pressure is directly related to density of gaseous substance.
Therefore, as air pressure in an area increases, the density of the gas particles in that area increases.
Answer:
Solvents are substances in which solutes dissolves while solutes are substances that dissolve in solvents and solutions result from mixing solvents and solutes.
Explanation:
- A solvent is a substance such as water that dissolves a solute.
- A solute is a substance that dissolves in a solvent. For example, when sodium chloride dissolves in water, sodium chloride is the solute and water is the solvent.
- A solution, on the other hand, results from combining a solute and a solvent. Therefore, a mixture of water and sodium chloride forms the solution.