For formation of a neutral ionic compound, the charges on cation and anion must be balanced. The cation is formed by loss of electrons by metals and anions are formed by gain of electrons by non metals.
The cations and anions being oppositely charged attract each other through strong coloumbic forces and form an ionic bond.
(1) Sodium is carrying +1 charge called as cation and chloride is an anion carrying -1 charge. Thus they combine and their oxidation states are exchanged and written in simplest whole number ratios to give neutral .
(2) Sodium is carrying +1 charge called as cation and phosphate is an anion carrying -3 charge. Thus they combine and their oxidation states are exchanged and written in simplest whole number ratios to give neutral .
(3) Sodium is carrying +1 charge called as cation and sulfate is an anion carrying -2 charge. Thus they combine and their oxidation states are exchanged and written in simplest whole number ratios to give neutral .
(4) Sodium is carrying +1 charge called as cation and carbonate is an anion carrying -2 charge. Thus they combine and their oxidation states are exchanged and written in simplest whole number ratios to give neutral .
(5) Potassium is carrying +1 charge called as cation and chloride is an anion carrying -1 charge. They form .
(6) Potassium is carrying +1 charge called as cation and phosphate is an anion carrying -3 charge. They form .
(7) Potassium is carrying +1 charge called as cation and sulfate is an anion carrying -2 charge. They form .
(8) Potassium is carrying +1 charge called as cation and carbonate is an anion carrying -2 charge. They form .
(9) Calcium is carrying +2 charge called as cation and chloride is an anion carrying -1 charge. They form .
(10) Calcium is carrying +2 charge called as cation and phosphate is an anion carrying -3 charge. They form .
(11) Calcium is carrying +2 charge called as cation and sulfate is an anion carrying -2 charge. They form .
(12) Calcium is carrying +2 charge called as cation and carbonate is an anion carrying -2 charge. They form .
(13) Ammonium ion is carrying +1 charge called as cation and chloride is an anion carrying -1 charge. They form .
(14) Ammonium ion is carrying +1 charge called as cation and phosphate is an anion carrying -3 charge. They form .
(15) Ammonium ion is carrying +1 charge called as cation and sulfate is an anion carrying -2 charge. They form .
(16) Ammonium ion is carrying +1 charge called as cation and carbonate is an anion carrying -2 charge. They form .
(17) Iron is carrying +3 charge called as cation and chloride is an anion carrying -1 charge. They form .
(18) Iron is carrying +3 charge called as cation and phosphate is an anion carrying -3 charge. They form .
(19) Iron is carrying +3 charge called as cation and sulfate is an anion carrying -2 charge. They form .
(20) Iron is carrying +3 charge called as cation and carbonate is an anion carrying -2 charge. They form .
Half-life refers to the time taken for half of the atoms in a radioactive substance to decay. Therefore in 1 half-life the 80 mg of substance will reduce to 40 mg. In another half-life it will reduce from 40 mg to 20 mg, then in a third half-life from 20 mg to 10 mg. Therefore the half-life is equal to the total time taken to decay from 80 mg to 10 mg divided by 3: t(1/2) = 36 hours / 3 = 12 hours.