Answer:
Initially 
of nitrogen dioxide were in the container .
Explanation:
Volume of the container at low pressure and at room temperature =
Number of moles in the container = 
After more addition of nitrogen gas at the same pressure and temperature.
Volume of the container after addition = 
Number of moles in the container after addition=
Applying Avogadro's law:
(at constant pressure and temperature)
Initially of nitrogen dioxide were in the container .
Answer:
The nucleus (center) of the atom contains the protons (positively charged) and the neutrons (no charge).
Explanation:
The nucleus (center) of the atom contains the protons (positively charged) and the neutrons (no charge).
The magnetic fields are the reason why magnets repel and attract. eachother.
Evaporation technique is used to separate a compound dissolved in a solvent by vaporizing the solvent and converting it to gaseous state. This leaves behind the solid residue present in the solution after the pure solvent is vaporized. The solvent vapors can be collected and condensed to get pure solvent. But the solid residue cannot be considered pure as it is the left over solid after all the solvent is evaporated. If the solution has some impurities, the solid left over includes all of the impurities. So, we cannot obtain a pure solid in evaporation technique.
