It's the law! Matter cannot be created or destroyed in chemical reactions. This is the law of conservation of mass. In every chemical reaction, the same mass of matter must end up in the products as started in the reactants.
120 grams of Carbon-14 decays to 15 grams in 17,190 years.
Fluorine has 9 protons and 9 electrons
Iodine has 53 protons and 53 electrons
First write all of the compounds/atoms in either side then fill in existing values and balance
Na- 1
Br- 1
Ca- 1
Cl- 2
Na- 1
Cl- 1
Ca-1
Br-2
Balance to get
2NaBr+CaCl2=2NaCl+CaBr2
