Answer:
Number of moles nitric acid in the cylinder is 400.539g/mol.
Explanation:
From the given,
Weight of empty gas cylinder
= 30.01 g/mol
Number of moles nitric acid =
=?
The mass of nitric acid in the cylinder = 

Number of moles of nitric acid =

Therefore, number of moles nitric acid in the cylinder is 400.539g/mol.
The correct option is B.
Coal dust refers to the powered form of coal. Because of the high surface area of coal dust it is highly prone to dust explosion, which involves rapid combustion of fine particles that are suspended in the air; this usually occur in an enclosed place. Coal dust in an enclosed place is more explosive than coal dust that is blown outdoor in an open space because the coal dust in an enclosed place is more concentrated due to restricted space, thus it is more liable to explosion.
Explanation:
Formation of crystals starts with formation of ions. After the formation of ions the bond formation takes place between the ions.
Bond making between the ions give rise to formation of cubic unit cell by placing them in such a fashion that it forms a shape of a cube.
These cube are then arranged in a repeated pattern which ultimately leads to the formation of crystals.
Hence, the order of steps:
Step 1 : Formation of ions
Step 2: Formation of ionic bonds
Step 3: Formation of cubes
Step 4: Formation of crystals
Answer:
C. The reaction can be broken down and performed in steps
Explanation:
Hess's Law of Constant Heat Summation states that irrespective of the number of steps followed in a reaction, the total enthalpy change for the reaction is the sum of all enthalpy changes corresponding to all the steps in the overall reaction. The implication of this law is that the change of enthalpy in a chemical reaction is independent of the pathway between the initial and final states of the system.
To obtain MgO safely without exposing magnesium to flame, the reaction sequence shown in the image attached may be carried out. Since the enthalpy of the overall reaction is independent of the pathway between the initial and final states of the system, the sum of the enthalpy of each step yields the enthalpy of formation of MgO.