The early hypothesis of Alfred wegener was based on observations that suggested continents were once joined together. later the theory of plate tectonics explained why large pieces of earths surfaces moves around and how many of earths features form.
but i this case c. continental drift and plate tectonics
The difference between ordinary, analar and industrial reagents is the in the purity. Ordinary reagents are those whose purity meets the standard. Analar reagents are used in chemical analysis and they are of high purity but with known contaminants which again illustrates their use in chemical analyses.Finally the industrial reagents are not pure enough and they are used for industrial purposes as well for commercial use.
Answer : The correct option is, (4) 6.0 mol
Explanation :
The given balanced chemical equation is,

In this reaction, lead undergoes reduction and chromium undergoes oxidation.
Oxidation reaction : It is the reaction in which a substance looses its electrons. In this oxidation state increases.
Reduction reaction : It is the reaction in which a substance gains electrons. In this oxidation state decreases.
Half reactions of oxidation-reduction are :
Oxidation : 
Reduction : 
From the reduction reaction, we conclude that 6 moles of electrons gained by the 3 moles of lead ions.
Hence, the correct option is, (4) 6.0 mole
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