Yes formation of a limestone caver is a physical change because a carving does not change the substance (limestone) it is still a limestone.
The atomic number is how many protons are in the nucleus of the atom. The atomic mass is how much mass is in the atom. Example: The atomic number of Helium is 2, and the atomic mass is 4. <span>To calculate the atomic number, simply count the protons.</span> <span>To </span>calculate<span> the </span>atomic mass<span> of an </span>atom,<span> add up the </span>mass<span> of </span>protons<span> and neutrons. Hope this helped! c:</span>
Nitrogen combine with hydrogen to produce ammonia 
at a 
ratio:
Assuming that the reaction has indeed proceeded to completion- with all nitrogen used up as the question has indicated. 
of hydrogen gas would have been consumed while 
of ammonia would have been produced. The final mixture would therefore contain
Apply the ideal gas law to find the total pressure inside the container and the respective partial pressure of hydrogen and ammonia:
of
and