Which of there is an indication that a chemical reaction has occurred?

a. freezing of substance

b. a change in color of a substance

c. melting of a substance

d. boiling of a substance

How many atoms of nickel can be found in a 1.00 g sample?

4*C: 4cm 8*C: 10cm 12*C: 14cm 16*C: 18cm 20*C:24cm 24*C: 12cm what is the independent variable, dependent variable and three constant variables?

How many moles of NaCi are equivalent to 15.6

Which term refers to the speed at which reactants are converted into products? A) reaction rate B) activation energy C) meta stable state D) spontaneous reaction

Given the system at equilibrium: 2POCl3 (g) + energy 2PCl3 (g) + O2 (g) Which changes occur when O2 (g) is added tothis system? (1) The equilibrium shifts to the right and the concentration of PCl3 (g) increases.

How much water should be added to 20 ml of 20 % alcohol solution to reduce the concentration to 10 %?

Calculate the theoretical atom economy for each reaction. a. 2 cuo (s) + c (s) → 2 cu (s) + co2 (g)

In the coordination compound (NH4) 2[Fe (OH2) F5], the Fe is octahedrally coordinated. (a) Based on the fact that F is a weak-field ligand, pre - dict whether this compound is diamagnetic or para - magnetic.

Which of these is a good conductor? 1) wood 2) air 3 ) silver 4) paper

Explain the energy transformation that must occur for your body to participate in a physical activity, such as playing a sport.