Which of the following is NOT a clue that a chemical reaction has taken place? A:release of gas
B:color change
C:mixing of the reactants
D:formation of a precipitate

Why is the melting of ice a physical change ?

What is the typical rotational frequency frot for a molecule like n2 at room temperature (25∘c)? assume that d for this molecule is 1å=10−10m. take the total mass of an n2 molecule to be mn2=4.65×10−26kg. you will need to account for rotations around two axes (not just one) to find the correct frequency. express frot numerically in hertz, to three significant figures.

Which of the following is described by the equation h2o(s)+ heat=h2o(i) a freezing melting condensing evaporating