JEE Main 2021 Question Paper (25-Jul-2021) (Shift 2)

Question 1

In the following the correct bond order sequence is:

Accepted Answer

$\mathrm{O}_2^{+} > \mathrm{O}_2 > \mathrm{O}_2^{-} > \mathrm{O}_2^{2-}$

Answer

$ {\mathrm{O}}_{2}^{2-}>{\mathrm{O}}_{2}^{+}>{\mathrm{O}}_{2}^{-}>{\mathrm{O}}_{2}$

Answer

$\mathrm{O}_2^{+} > \mathrm{O}_2^{-} > \mathrm{O}_2^{2-} > \mathrm{O}_2$

Answer

$\mathrm{O}_2 > \mathrm{O}_2^- > \mathrm{O}_2^{2-} > \mathrm{O}_2^{+}$

Question 2

A biodegradable polyamide can be made from:

Accepted Answer

$ \mathrm{Glycine} \quad \mathrm{and} \quad \mathrm{aminocaproic} \quad \mathrm{acid} $

Answer

$ \mathrm{Glycine}\quad \mathrm{and}\quad \mathrm{isoprene}$

Answer

$\mathrm{Hexamethylene\ diamine\ and\ adipic\ acid}$

Answer

$\mathrm{Styrene} \quad \mathrm{and} \quad \mathrm{caproic} \quad \mathrm{acid}$

Question 3

Match List I with List II :

	List-I Elements		List-II Properties
(a)	$ \mathrm{Li}$	(i)	Poor water solubility of $ {\mathrm{I}}^{-}$salt
(b)	$ \mathrm{Na}$	(ii)	Most abundant element in cell fluid
(c)	$ \mathrm{K}$	(iii)	Bicarbonate salt used in fire extinguisher
(d)	$ \mathrm{Cs}$	(iv)	Carbonate salt decomposes easily on heating

Choose the correct answer from the options given
below:

Accepted Answer

$ \left(\mathrm{a}\right)-\left(\mathrm{iv}\right),\quad \left(\mathrm{b}\right)-\left(\mathrm{iii}\right),\quad \left(\mathrm{c}\right)-\left(\mathrm{ii}\right),\quad \left(\mathrm{d}\right)-\left(\mathrm{i}\right)$

Answer

$(\mathrm{a}) - (\mathrm{i}), \quad (\mathrm{b}) - (\mathrm{iii}), \quad (\mathrm{c}) - (\mathrm{ii}), \quad (\mathrm{d}) - (\mathrm{iv})$

Answer

$(\mathrm{a}) - (\mathrm{iv}), \quad (\mathrm{b}) - (\mathrm{ii}), \quad (\mathrm{c}) - (\mathrm{iii}), \quad (\mathrm{d}) - (\mathrm{i})$

Answer

$(\mathrm{a}) - (\mathrm{i}), \quad (\mathrm{b}) - (\mathrm{ii}), \quad (\mathrm{c}) - (\mathrm{iii}), \quad (\mathrm{d}) - (\mathrm{iv})$

Question 4

Which one of the following metal complexes is most stable?

Accepted Answer

$\left[\mathrm{Co}(\mathrm{en})_{3}\right]\mathrm{Cl}_{2}$

Answer

$ \left[\mathrm{Co}\left(\mathrm{en}\right){\left({\mathrm{NH}}_{3}\right)}_{4}\right]{\mathrm{Cl}}_{2}$

Answer

$\left[\mathrm{Co}(\mathrm{en})_{2}(\mathrm{NH}_{3})_{2}\right]\mathrm{Cl}_{2}$

Answer

$\left[\mathrm{Co}\left(\mathrm{NH}_3\right)_6\right]\mathrm{Cl}_2$

Question 5

Match List I with List II : (Both having metallurgical terms) List-I List-II (a) Concentration of $ \mathrm{Ag}$ ore (i) Reverberatory furnace (b) Blast furnace (ii) Pig iron (c) Blister copper (iii) Leaching with dilute $ \mathrm{NaCN}$ solution (d) Froth floatation method (iv) Sulfide ores Choose the correct answer from the options given below:

Accepted Answer

$ \left(\mathrm{a}\right)-\left(\mathrm{iii}\right),\quad \left(\mathrm{b}\right)-\left(\mathrm{ii}\right),\quad \left(\mathrm{c}\right)-\left(\mathrm{i}\right),\quad \left(\mathrm{d}\right)-\left(\mathrm{iv}\right)$

Answer

$(\mathrm{a}) - (\mathrm{iii}), \quad (\mathrm{b}) - (\mathrm{iv}), \quad (\mathrm{c}) - (\mathrm{i}), \quad (\mathrm{d}) - (\mathrm{ii})$

Answer

$(\mathrm{a}) - (\mathrm{iv}), \quad (\mathrm{b}) - (\mathrm{i}), \quad (\mathrm{c}) - (\mathrm{iii}), \quad (\mathrm{d}) - (\mathrm{ii})$

Answer

$(\mathrm{a}) - (\mathrm{iv}), \quad (\mathrm{b}) - (\mathrm{iii}), \quad (\mathrm{c}) - (\mathrm{ii}), \quad (\mathrm{d}) - (\mathrm{i})$

	List-I		List-II
(a)	Concentration of $ \mathrm{Ag}$ ore	(i)	Reverberatory furnace
(b)	Blast furnace	(ii)	Pig iron
(c)	Blister copper	(iii)	Leaching with dilute $ \mathrm{NaCN}$ solution
(d)	Froth floatation method	(iv)	Sulfide ores