Which of the following represents a rule for balancing a nuclear equation?
i. the total number of protons plus neutrons in the products and reactants must be the same
ii. the total number of each type of element in the products and reactants must be the same
iii. the total number of nuclear charges in the products and reactants must be the same
iv. the total number of each type of elementary particle in the products and reactants must be the same.

The correct answer is 1 the total number of proton plus neutrons in the products and reactants must be same.

Explanation:

During a radioactive reaction the nucleus of the radioactive atom undergo disintegration or breakdown to form new nucleus.

   Radioactive disintegration deals with the emission of α particle or β particle from a radioactive nucleus resulting in the formation of new nucleus.Although new nucleus is formed the total number of proton plus neutrons in product and reactant must be same.

n has four pairs of electrons in the valence shell, electrons repel one another ,n has 7 protons in its nucleus, and since n has 7 protons, it must fill the second shell, giving it 4 pairs of electrons. the electrons form 3 bonds and 1 lone pair of electrons. each pair of electrons repels the other pairs, so they are equally far apart.

so all of the above

pure water does not conduct electricity very well. however, when certain substances are dissolved in water, the solution does conduct electricity. you can make a simple device that shows how well a solution conducts electricity. this device uses a flashlight bulb to indicate how well the solution conducts electricity. the better the solution conducts electricity, the brighter the bulb will glow.

explanation: