pKa increases in benzoic acid when substituent "x" is bonded at para-position, then "x" is
-COOH
-NO2
-CN
-OCH3
D.
-OCH3
Larger the value of pKa smaller will be its acidity. Out of the four groups, -COOH, -NO2 and -CN are e- withdrawing which makes benzoic acid more acidic whereas -OCH3 is e- donating which reduces the acidity (makes H less easily available). pKa value increases if OCH3 is present at para-position of benzoic acid.
Assertion : Aqueous solution of CoCl2 is pink in colour. It turns blue in presence of conc. HCl.
Reason : It is due to the formation of [CoCl4]2-.
If both assertion and reason are true and reason is the correct explanation of assertion.
If both assertion and reason are true but reason is not the correct explanation of assertion.
If assertion is true but reason is false.
If both assertion and reason are false.
The concentration of Ag+ ion in a given saturated solution of AgCl at 25°C is 1.06 x 10-5 g ion L-1 .Thus , the solubility product of AgCl is :
0.453 x 10-10
0.530 x 10-10
1.12 x 10-10
2.12 x 10-10
Solution of 0.l N NH4OH and 0.1 N NH4Cl has pH 9.25. Then , pKb of NH4OH is :
9.75
4.75
3.75
8.25