1
JEE Main 2022 (Online) 27th July Evening Shift
+4
-1

The plot of $$\mathrm{pH}$$-metric titration of weak base $$\mathrm{NH}_{4} \mathrm{OH}$$ vs strong acid HCl looks like :

A
B
C
D
2
JEE Main 2022 (Online) 26th July Evening Shift
+4
-1

Class XII students were asked to prepare one litre of buffer solution of $$\mathrm{pH} \,8.26$$ by their Chemistry teacher: The amount of ammonium chloride to be dissolved by the student in $$0.2\, \mathrm{M}$$ ammonia solution to make one litre of the buffer is :

(Given: $$\mathrm{pK}_{\mathrm{b}}\left(\mathrm{NH}_{3}\right)=4.74$$

Molar mass of $$\mathrm{NH}_{3}=17 \mathrm{~g} \mathrm{~mol}^{-1}$$

Molar mass of $$\mathrm{NH}_{4} \mathrm{Cl}=53.5 \mathrm{~g} \mathrm{~mol}^{-1}$$ )

A
53.5 g
B
72.3 g
C
107.0 g
D
126.0 g
3
JEE Main 2022 (Online) 25th July Evening Shift
+4
-1

$${K_{{a_1}}}$$, $${K_{{a_2}}}$$ and $${K_{{a_3}}}$$ are the respective ionization constants for the following reactions (a), (b) and (c).

(a) $${H_2}{C_2}{O_4} \mathbin{\lower.3ex\hbox{\buildrel\textstyle\rightarrow\over {\smash{\leftarrow}\vphantom{_{\vbox to.5ex{\vss}}}}}} {H^ + } + H{C_2}O_4^ -$$

(b) $$H{C_2}O_4^ - \mathbin{\lower.3ex\hbox{\buildrel\textstyle\rightarrow\over {\smash{\leftarrow}\vphantom{_{\vbox to.5ex{\vss}}}}}} {H^ + } + {C_2}O_4^{2 - }$$

(c) $${H_2}{C_2}O_4^{} \mathbin{\lower.3ex\hbox{\buildrel\textstyle\rightarrow\over {\smash{\leftarrow}\vphantom{_{\vbox to.5ex{\vss}}}}}} 2{H^ + } + {C_2}O_4^{2 - }$$

The relationship between $${K_{{a_1}}}$$, $${K_{{a_2}}}$$ and $${K_{{a_3}}}$$ is given as :

A
$${K_{{a_3}}}$$ $$=$$ $${K_{{a_1}}}$$ $$+$$ $${K_{{a_2}}}$$
B
$${K_{{a_3}}}$$ $$=$$ $${K_{{a_1}}}$$ $$-$$ $${K_{{a_2}}}$$
C
$${K_{{a_3}}}$$ $$=$$ $${K_{{a_1}}}$$ $$/$$ $${K_{{a_2}}}$$
D
$${K_{{a_3}}}$$ $$=$$ $${K_{{a_1}}}$$ $$\times$$ $${K_{{a_2}}}$$
4
JEE Main 2022 (Online) 25th July Morning Shift
+4
-1

$$20 \mathrm{~mL}$$ of $$0.1\, \mathrm{M} \,\mathrm{NH}_{4} \mathrm{OH}$$ is mixed with $$40 \mathrm{~mL}$$ of $$0.05 \mathrm{M} \mathrm{HCl}$$. The $$\mathrm{pH}$$ of the mixture is nearest to :

(Given : $$\mathrm{K}_{\mathrm{b}}\left(\mathrm{NH}_{4} \mathrm{OH}\right)=1 \times 10^{-5}, \log 2=0.30, \log 3=0.48, \log 5=0.69, \log 7=0.84, \log 11= 1.04)$$

A
3.2
B
4.2
C
5.2
D
6.2
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