How do you find the number of isotopes in an element?

If you burn 10 kilograms of wood in a fire (combustion) what is the weight of the products after the fire has finished burning the wood?

Upon decomposition, one sample of magnesium fluoride produced 1.65 kg of magnesium and 2.56 kg of fluorine. a second sample produced 1.32 kg of magnesium. part a how much fluorine (in grams) did the second sample produce?

The velocity of any object depends upon a) the location of the object. b) the location of the observer. c) which measurement tools are used. d) the relative motion of the observer.