the number of atoms? if the chemical change happens in a closed space, all the atoms are still present in one form or another. In another words, chemical reactions follows the principle of conservation of mass. This principle is founded on the assumption that matter can neither be created or destroyed. Thus, the total mass of all compounds prior to the chemical change/reaction should be the same as the total mass of all compounds after the chemical change.
example: you burn wood, it releases all kinds of chemicals in the smoke, water vapor, and ashes. if you could collect all the water vapor and the smoke, you would still have the same number of atoms - now they would have less energy (since the heat produced from burning them is gone) but there would still be the same number of atoms, albeit in different compounds probably.
Physical.
No, new substances are not formed in a physical change. A physical change is a change in the form or appearance of a substance without changing its chemical composition.
physical because a chemical change means it can never form back
In general, a substance produced during a chemical change cannot be easily changed back into the original substance. Chemical changes are characterized by the formation of new substances with different chemical properties than the original substances. Reversing a chemical change typically requires a different set of reactions or processes.
it is neither. no chemical reaction or physical change (melting boiling etc) can change net mass only nuclear reactions change the over all mass by converting mass to energy via Einstein's famous E=MC^2 equation
A physical change can be reversed, for it does not change what the object is made of. The glass, even when broken, is still glass. It can be put back into its original state (possibly through melting) because it never changed what it was made out of.
When a aluminum can is crushed, it undergoes a physical change, because even though the object got crushed and misshaped it still has the same identity.The identity has never changed.
An aggregate constant is a nonscalar constant which value never change or are not changed during execution of the program.
It depends if the change is physical or chemical. If it is a physical change, the wood or iron never really changed, just it's physical appearance. If the change is chemical then the wood or iron supposedly can't change back to it's original substance or matter.
Germany's name never changed during the Holocaust.
In a physical change, the chemical composition of the substance remains the same, but some physical properties like shape, size, or state may change. This means that the substance can be reversed back to its original state without undergoing a chemical reaction.
He never changed his name.
physical because a chemical change means it can never form back
There were many things that changed during the Renaissance. Such as the art, literature, and even religion which would have never be allowed in medieval times. The Renaissance was a whole change of mind. :)
No country has never changed. The science "anthropology"is founded on the premis that all socities are in a state of continuous change.
Physical.
No, new substances are not formed in a physical change. A physical change is a change in the form or appearance of a substance without changing its chemical composition.