1
JEE Main 2022 (Online) 28th July Morning Shift
MCQ (Single Correct Answer)
+4
-1
Change Language

In which of the following pairs, electron gain enthalpies of constituent elements are nearly the same or identical?

(A) Rb and Cs

(B) Na and K

(C) Ar and Kr

(D) I and At

Choose the correct answer from the options given below :

A
(A) and (B) only
B
(B) and (C) only
C
(A) and (C) only
D
(C) and (D) only
2
JEE Main 2022 (Online) 28th July Morning Shift
MCQ (Single Correct Answer)
+4
-1
Out of Syllabus
Change Language

Which of the reaction is suitable for concentrating ore by leaching process ?

A
$$ 2 \mathrm{Cu}_{2} \mathrm{~S}+3 \mathrm{O}_{2} \rightarrow 2 \mathrm{Cu}_{2} \mathrm{O}+2 \mathrm{SO}_{2} $$
B
$$\mathrm{Fe}_{3} \mathrm{O}_{4}+\mathrm{CO} \rightarrow 3 \mathrm{FeO}+\mathrm{CO}_{2}$$
C
$$\mathrm{Al}_{2} \mathrm{O}_{3}+2 \mathrm{NaOH}+3 \mathrm{H}_{2} \mathrm{O} \rightarrow 2 \mathrm{Na}\left[\mathrm{Al}(\mathrm{OH})_{4}\right]$$
D
$$\mathrm{Al}_{2} \mathrm{O}_{3}+6 \mathrm{Mg} \rightarrow 6 \mathrm{MgO}+4 \mathrm{Al}$$
3
JEE Main 2022 (Online) 28th July Morning Shift
MCQ (Single Correct Answer)
+4
-1
Out of Syllabus
Change Language

The metal salts formed during softening of hardwater using Clark's method are :

A
$$\mathrm{Ca}(\mathrm{OH})_{2}$$ and $$\mathrm{Mg}(\mathrm{OH})_{2}$$
B
$$\mathrm{CaCO}_{3}$$ and $$\mathrm{Mg}(\mathrm{OH})_{2}$$
C
$$\mathrm{Ca}(\mathrm{OH})_{2}$$ and $$\mathrm{MgCO}_{3}$$
D
$$\mathrm{CaCO}_{3}$$ and $$\mathrm{MgCO}_{3}$$
4
JEE Main 2022 (Online) 28th July Morning Shift
MCQ (Single Correct Answer)
+4
-1
Out of Syllabus
Change Language

Which of the following statement is incorrect?

A
Low solubility of LiF in water is due to its small hydration enthalpy.
B
$$\mathrm{KO}_{2}$$ is paramagnetic.
C
Solution of sodium in liquid ammonia is conducting in nature.
D
Sodium metal has higher density than potassium metal.
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