Which of these is true of the Earth system?
a. Energy rarely enters or leaves the system.
b. Matter rarely enters or leaves the system.
c. Matter easily enters the system but cannot
leave the system.
d. Energy easily enters the system but cannot leave the system.

the density(ratio between mass and volume as m/v) decreases from top to bottom in periodic table group as the size increases and nuclear charge decreases. but in periods density increases from left to right as atom size decreases and nuclear charge increases.

un recipient conține 6,4 moli de gaz. gazul hidrogen reprezintă 25% din totalul kilometrilor din container. în cazul în care presiunea totală este de 1.24 atm ceea ce este