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1

JEE Main 2021 (Online) 27th August Evening Shift

MCQ (Single Correct Answer)
Which one of the following is formed (mainly) when red phosphorus is heated in a sealed tube at 803 K?
A
White phosphorus
B
Yellow phosphorus
C
$$\beta$$-Black phosphorus
D
$$\alpha$$-Black phosphorus

Explanation

When red phosphorus is heated in a sealed tube at 803 K, $$\alpha$$-Black phosphorus is formed.
2

JEE Main 2021 (Online) 27th August Morning Shift

MCQ (Single Correct Answer)
In polythionic acid, H2SxO6 (x = 3 to 5) the oxidation state(s) of sulphur is/are :
A
+ 5 only
B
+ 6 only
C
+ 3 and + 5 only
D
0 and + 5 only

Explanation

3

JEE Main 2021 (Online) 26th August Evening Shift

MCQ (Single Correct Answer)
The number of non-ionisable hydrogen atoms present in the final product obtained from the hydrolysis of PCl5 is :
A
0
B
2
C
1
D
3

Explanation



Here all hydrogens are ionisable.

$$\therefore$$ Answer is zero.
4

JEE Main 2021 (Online) 27th July Evening Shift

MCQ (Single Correct Answer)
Match List - I with List - II :

List - I
(compound)
List - II
(effect/affected species)
(a) Carbon monoxide (i) Carcinogenic
(b) Sulphur dioxide (ii) Metabolized by pyrus plants
(c) Polychlorinated biphenyls (iii) haemoglobin
(d) Oxides of Nitrogen (iv) Stiffness of flower buds


Choose the correct answer from the options given below :
A
(a) - (iii), (b) - (iv), (c) - (i), (d) - (ii)
B
(a) - (iv), (b) - (i), (c) - (iii), (d) - (ii)
C
(a) - (i), (b) - (ii), (c) - (iii), (d) - (iv)
D
(a) - (iii), (b) - (iv), (c) - (ii), (d) - (i)

Explanation

A. If haemoglobin binds CO, it prevents the binding of O2 to haemoglobin due to the competition for same binding sites.

B. Higher conc. SO2 in air can cause stiffness of flower buds.

C. Polychlorinated biphenyls are carcinogenic (cancer causing) in humans as well as animals.

D. Certain plants, e.g. pinus, Juniparus, quercus, pyrus and vitis can metabolise nitrogen oxides. Hence, the correct match is

(a) - (iii), (b) - (iv), (c) - (i), (d) - (ii)

Questions Asked from p-Block Elements

On those following papers in MCQ (Single Correct Answer)
Number in Brackets after Paper Indicates No. of Questions
JEE Main 2022 (Online) 24th June Evening Shift [ Memory Based ] (1)
JEE Main 2022 (Online) 24th June Morning Shift [ Memory Based ] (2)
JEE Main 2021 (Online) 1st September Evening Shift (1)
JEE Main 2021 (Online) 31st August Evening Shift (1)
JEE Main 2021 (Online) 27th August Evening Shift (1)
JEE Main 2021 (Online) 27th August Morning Shift (1)
JEE Main 2021 (Online) 26th August Evening Shift (1)
JEE Main 2021 (Online) 27th July Evening Shift (2)
JEE Main 2021 (Online) 27th July Morning Shift (1)
JEE Main 2021 (Online) 22th July Evening Shift (2)
JEE Main 2021 (Online) 20th July Morning Shift (2)
JEE Main 2021 (Online) 18th March Morning Shift (3)
JEE Main 2021 (Online) 16th March Evening Shift (1)
JEE Main 2021 (Online) 16th March Morning Shift (3)
JEE Main 2021 (Online) 26th February Evening Shift (1)
JEE Main 2021 (Online) 26th February Morning Shift (1)
JEE Main 2021 (Online) 25th February Evening Shift (2)
JEE Main 2021 (Online) 25th February Morning Shift (1)
JEE Main 2020 (Online) 6th September Evening Slot (2)
JEE Main 2020 (Online) 6th September Morning Slot (1)
JEE Main 2020 (Online) 5th September Evening Slot (2)
JEE Main 2020 (Online) 4th September Morning Slot (1)
JEE Main 2020 (Online) 3rd September Morning Slot (2)
JEE Main 2020 (Online) 2nd September Morning Slot (1)
JEE Main 2020 (Online) 8th January Evening Slot (2)
JEE Main 2020 (Online) 7th January Evening Slot (1)
JEE Main 2019 (Online) 12th April Evening Slot (1)
JEE Main 2019 (Online) 12th April Morning Slot (1)
JEE Main 2019 (Online) 10th April Evening Slot (2)
JEE Main 2019 (Online) 9th April Evening Slot (1)
JEE Main 2019 (Online) 9th April Morning Slot (1)
JEE Main 2019 (Online) 8th April Morning Slot (1)
JEE Main 2019 (Online) 12th January Evening Slot (1)
JEE Main 2019 (Online) 12th January Morning Slot (1)
JEE Main 2019 (Online) 11th January Morning Slot (1)
JEE Main 2019 (Online) 10th January Evening Slot (1)
JEE Main 2019 (Online) 9th January Evening Slot (1)
JEE Main 2019 (Online) 9th January Morning Slot (2)
JEE Main 2018 (Online) 16th April Morning Slot (2)
JEE Main 2018 (Offline) (1)
JEE Main 2018 (Online) 15th April Evening Slot (3)
JEE Main 2018 (Online) 15th April Morning Slot (2)
JEE Main 2017 (Online) 9th April Morning Slot (3)
JEE Main 2017 (Online) 8th April Morning Slot (2)
JEE Main 2017 (Offline) (1)
JEE Main 2016 (Online) 10th April Morning Slot (3)
JEE Main 2016 (Online) 9th April Morning Slot (3)
JEE Main 2016 (Offline) (2)
JEE Main 2015 (Offline) (3)
JEE Main 2014 (Offline) (3)
AIEEE 2012 (1)
AIEEE 2011 (3)
AIEEE 2009 (1)
AIEEE 2008 (2)
AIEEE 2007 (2)
AIEEE 2006 (3)
AIEEE 2005 (5)
AIEEE 2004 (5)
AIEEE 2003 (7)
AIEEE 2002 (7)

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