JEE Main 2021 (Online) 31st August Morning Shift | Environmental Chemistry Question 21 | Chemistry

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JEE Main 2021 (Online) 31st August Morning Shift

MCQ (Single Correct Answer)

-1

BOD values (in ppm) for clean water (A) and polluted water (B) are expected respectively :

A > 50, B < 27

A > 25, B < 17

A < 5, B > 17

A > 15, B > 47

JEE Main 2021 (Online) 27th August Evening Shift

MCQ (Single Correct Answer)

-1

In stratosphere most of the ozone formation is assisted by :

cosmic rays

$$\gamma$$-rays

ultraviolet radiation

visible radiations

JEE Main 2021 (Online) 27th August Morning Shift

MCQ (Single Correct Answer)

-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 :

$$Cl\mathop O\limits^ \bullet + \mathop C\limits^ \bullet {F_2}Cl$$

$$Cl\mathop O\limits^ \bullet + C\mathop {{H_3}}\limits^ \bullet $$

$$\mathop C\limits^ \bullet {H_3} + C\mathop {{F_2}}\limits^ \bullet Cl$$

$$\mathop C\limits^ \bullet l + C\mathop {{F_2}}\limits^ \bullet Cl$$

JEE Main 2021 (Online) 26th August Evening Shift

MCQ (Single Correct Answer)

-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 :

Both (A) and (R) are true but (R) is not the true explanation of (A)

(A) is false but (R) is true.

(A) is true but (R) is false.

Both (A) and (R) are true and (R) is the true explanation of (A)

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