1
JEE Main 2021 (Online) 31st August Morning Shift
MCQ (Single Correct Answer)
+4
-1
BOD values (in ppm) for clean water (A) and polluted water (B) are expected respectively :
A
A > 50, B < 27
B
A > 25, B < 17
C
A < 5, B > 17
D
A > 15, B > 47
2
JEE Main 2021 (Online) 27th August Evening Shift
MCQ (Single Correct Answer)
+4
-1
In stratosphere most of the ozone formation is assisted by :
A
cosmic rays
B
$$\gamma$$-rays
C
ultraviolet radiation
D
visible radiations
3
JEE Main 2021 (Online) 27th August Morning Shift
MCQ (Single Correct Answer)
+4
-1
The gas 'A' is having very low reactivity reaches to stratosphere. It is non-toxic and non-flammable but dissociated by UV-radiations in stratosphere. The intermediates formed initially from the gas 'A' are :
A
$$Cl\mathop O\limits^ \bullet + \mathop C\limits^ \bullet {F_2}Cl$$
B
$$Cl\mathop O\limits^ \bullet + C\mathop {{H_3}}\limits^ \bullet $$
C
$$\mathop C\limits^ \bullet {H_3} + C\mathop {{F_2}}\limits^ \bullet Cl$$
D
$$\mathop C\limits^ \bullet l + C\mathop {{F_2}}\limits^ \bullet Cl$$
4
JEE Main 2021 (Online) 26th August Evening Shift
MCQ (Single Correct Answer)
+4
-1
Given below are two statements : one is labelled as Assertion (A) and the other is labelled as Reason (R).

Assertion (A) : Photochemical smog causes cracking of rubber.

Reason (R) : Presence of ozone, nitric oxide, acrolein, formaldehyde and peroxyacetyl nitrate in photochemical smog makes it oxidizing.

Choose the most appropriate answer from the options given below :
A
Both (A) and (R) are true but (R) is not the true explanation of (A)
B
(A) is false but (R) is true.
C
(A) is true but (R) is false.
D
Both (A) and (R) are true and (R) is the true explanation of (A)
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