False, because physical change does not involve the formation of substances. An example of physical change is change of state e.g water freezing .It is still water if you were to melt it.
Answer:
The new findings support the theory that walking first arose underwater, preceding the move onto land and the development of toes and limbs adapted to land perambulation.
To solve this problem, we assume ideal gas so that we can
use the formula:
PV = nRT
since the volume of the flask is constant and R is
universal gas constant, so we can say:
n1 T1 / P1 = n2 T2 / P2
1.9 mol * (21 + 273 K) / 697 mm Hg = n2 * (26 + 273 K) /
841 mm Hg
<span>n2 = 2.25 moles</span>
Answer:
2KCl + F₂ → 2KF + Cl₂
Explanation:
Law of conservation of mass:
According to the law of conservation mass, mass can neither be created nor destroyed in a chemical equation.
This law was given by French chemist Antoine Lavoisier in 1789. According to this law mass of reactant and mass of product must be equal, because masses are not created or destroyed in a chemical reaction.
2KCl + F₂ → 2KF + Cl₂
In this equation mass of reactant and product is equal. There are 2 potassium 2 chlorine and fluorine atoms on both side of equation it means mass remain conserved.
All other options are incorrect because mass is not conserved.
Mg₂ + LiBr ---> LiMg + Br
In this equation mass of magnesium is more on reactant side.
Na +O₂ ---> Na₂O
In this equation there is more oxygen and less sodium on reactant side while there is more sodium and less oxygen on product side.
H₂O ---> H₂ + O₂
In this equation there is less oxygen on reactant side while more oxygen on product side.
