Propane : ).............................................
Answer:
The volume of the solution is 0.305 liters.
Explanation:
Molar mass is the amount of mass that a substance contains in one mole. The molar mass of K₂Cr₂O₇ is 294 g / mole. Then you can apply the following rule of three: if by definition of molar mass 294 grams of the compound are contained in 1 mole, 180 grams are contained in how many moles?

moles= 0.61
Molarity is a measure of the concentration of a substance that is defined as the number of moles contained in a certain volume. So, the molarity of a solution is calculated by dividing the moles of the solute by the volume of the solution:

Molarity is expressed in units
.
In this case:
- molarity= 2 M
- number of moles of solute= 0.61 moles
- volume= ?
Replacing in the definition of molarity:

Solving:

volume= 0.305 liters
<u><em>The volume of the solution is 0.305 liters.</em></u>
Answer:
A is the correct answer.
Explanation:
An atom consist of electron, protons and neutrons. Protons and neutrons are present with in nucleus while the electrons are present out side the nucleus.
All these three subatomic particles construct an atom. A neutral atom have equal number of proton and electron. In other words we can say that negative and positive charges are equal in magnitude and cancel the each other. For example if neutral atom has 6 protons than it must have 6 electrons. The sum of neutrons and protons is the mass number of an atom while the number of protons are number of electrons is the atomic number of an atom.
For example in case of Helium:
The 1st one diagram shows that arrow is pointing with in nucleus. The helium nucleus contain two protons and two neutrons. Thus maximum mass is present with in nucleus. while two electrons are revolve around the nucleus and mass of electron is negligible.