Stoichiometry
A sample of well water contains 140 gm/m³ Ca²⁺ ions and 345 gm/m³ Na⁺ ions. The hardness of the sample of water, expressed in terms of equivalent CaCO₃ in gm/m³ is (assuming atomic masses of Ca :40, Na : 23, C : 12, O : 16)

350
345
485
140

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Stoichiometry
Pick out the wrong statement about the recycle stream in a process.

The ratio of the quantity of a reactant present in the reactor feed of a recycling operation to the quantity of the same reactant entering the process as fresh feed is called combined feed ratio
Recycling in a process does not help in getting higher extent of reaction
Recycling in a process stream helps in utilising the valuable reactants to the maximum with minimum loss of reactants
Recycling is exemplified by refluxing back a part of the distillate to the distillation column to maintain the quantity of liquid within the column

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