1
JEE Main 2021 (Online) 24th February Evening Shift
MCQ (Single Correct Answer)
+4
-1
Change Language
Given below are two statements : one is labelled as Assertion A and the other is labelled as Reason R.

Assertion A : Hydrogen is the most abundant element in the Universe, but it is not the most abundant gas in the troposphere.

Reason R : Hydrogen is the lightest element.

In the light of the above statements, choose the correct answer from the options given below :
A
Both A and R are true but R is NOT the correct explanation of A
B
Both A and R are true and R is the correct explanation of A
C
A is true but R is false
D
A is false but R is true.
2
JEE Main 2021 (Online) 24th February Evening Shift
MCQ (Single Correct Answer)
+4
-1
Change Language
Given below are two statements :

Statement I : The value of the parameter "Biochemical Oxygen Demand (BOD)" is important for survival of aquatic life.

Statement II : The optimum value of BOD is 6.5 ppm.

In the light of the above statements, choose the most appropriate answer from the options given below :
A
Statement I is false but Statement II is true
B
Statement I is true but Statement II is false
C
Both Statement I and Statement II are true
D
Both Statement I and Statement II are false
3
JEE Main 2021 (Online) 24th February Morning Shift
MCQ (Single Correct Answer)
+4
-1
Change Language
The gas released during anaerobic degradation of vegetation may lead to :
A
Ozone hole
B
Corrosion of metals
C
Acid rain
D
Global warming and cancer
4
JEE Main 2020 (Online) 6th September Morning Slot
MCQ (Single Correct Answer)
+4
-1
The presence of soluble fluoride ion upto 1 ppm concentration in drinking water, is :
A
safe for teeth
B
harmful to skin
C
harmful for teeth
D
harmful to bones
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