Entries of Column-I are to be matched with entries of Column-II. Each entry of Column-I may have the matching with one or more than one entries of Column-II. Column-I contains four statements followin

Question

Entries of Column-I are to be matched with entries of Column-II. Each entry 
of Column-I may have the matching with one or more than one entries of 
Column-II. Column-I contains four statements following reason and Column-II 
consists of four options P, Q, R, S. Answer the following : P $\rightarrow$ If 
both statement and reason are true and reason is correct explanation of 
statement. Q $\rightarrow$ If both statement and reason are true and reason is 
not correct explanation of statement. R $\rightarrow$ If statement is correct 
and reason is incorrect. S $\rightarrow$ If both statement and reason are 
incorrect.

Prashant Kotian · Accepted Answer

Correct answer: A-Q, B-P, C-R, D-S. Step 1: The conversion between chromate (CrO4^2-) and dichromate (Cr2O7^2-) is pH-dependent. Chromate is stable in basic/neutral conditions, while dichromate is stable in acidic conditions. Step 2: Increasing acidity (lowering pH to an acidic value, x < 7, e.g., 6) converts yellow chromate to orange dichromate: 2CrO4^2- + 2H+ <=> Cr2O7^2- + H2O. Conversely, adding base (raising pH to a basic value, y > 7, e.g., 8) shifts the equilibrium back to chromate. Step 3: Thus, x must be acidic (6) and y must be basic (8), which corresponds to option (a).

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