Because an excess of carbon dioxide could lead to global warming and affect climate drastically causing it to be warmer and destroy habitats such as penguins or polar bears.
Atomic number is equal to the number of protons and electrons
Atomic mass - protons = neutrons
protons + neutrons = atomic mass
I hope this helps
Text book: We can measure the mass of the text book easily by weighing machine, to measure the volume we need to measure the length, width, and height of the text book by the ruler, by multiplying these dimension we can get the volume of the text book, and by dividing the mass of the book with its volume we can get the density of the book.
Milk Container: We can measure the mass of the milk container easily by weighing machine, now (assuming the milk container is cylindrical in shape) we need to measure its height, and and diameter and by the formula (π*r^2*h) we can measure its volume, and and by dividing the mass with its volume we can get the density of the milk container.
Air filled balloon: we can measure the mass of the air filled balloon by weighing it weight machine, we know that the density of air is 28.97 kg/m^3, by dividing the mass of the balloon with the denisty of air we can get the volume of the balloon.
