If the ending substance has changed its properties. For example if iron rusts it is a chemical change because it is no longer the same as before it is now just rust. A physical change only changes the appearance but burning something or changing it's chemical properties is a chemical change.
Answer: b.) they tend to lose electrons to gain stability
Explanation:
Answer:
I think its A. Because space has no gravity..
Explanation:
Answer: Yes, a given amount of Hydrogen would react with different masses of the two isotopes of chlorine, and no, this does <em>not</em> conflict with the Law of Definite proportions
Explanation:
About 76% percent of Cl is found in the Cl-35 isotope, and about 24% in the Cl.37 isotope. that means that about 24% of Cl nuclei have 2 more neutrons than the average Cl nucleus.
So, if 
reacts with 
, 76% of the Hydrogen that reacted will react with Cl-35, and the rest will react with Cl-37. Why does this not conflict with the law of definite proportions? Because each Hydrogen atom ends up paired to a single Chlorine atom! Moreover, the proportion of Cl-35 to Cl-37 remains constant in all samples of Chlorine that are naturally found, thus we will always find the same proportion of Chlorine to Hydrogen in any HCl sample we come across. Thus the weight of a mol of Cl will always be 
or 35.45 if we had done this calculation with more significant digits.
Therefore 1 mol of (2 grams) will always react with 1 mol of (35.45g*2=70.9 grams), and this is a definite proportion.
