The first one is 2
The second is 1
The third is 6
And the fourth is 3
Conductivity is a measurement of the ability of an aqueous solution to transfer an electrical current.
Explanation:
To calculate the conductivity of a solution you simply multiply the concentration of each ion in solution by its molar conductivity and charge then add these values for all ions in solution.
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The reaction creates dihydrogen, hence if it's uncontrolled it could lead to potentially dangerous amounts of gas being released at once.