Practice problems on JEE Mains, JEE Mains 2021 Aug 31 Shift 1

Question 1

Match List-I with List-II.List-I(a) Torque(b) Impulse(c) Tension(d) SurfaceList-II(i) MLT-1(ii) MT−2 (iii) ML2 T−2 (iv) MLT-2Choose the most appropriate answer from the option given below:

Accepted Answer

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

Answer

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

Answer

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

Answer

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

Question 2

Which one of the following compounds contains β−C1​−C4​ glycosidic linkage?

Accepted Answer

Lactose

Answer

Maltose

Answer

Sucrose

Answer

Amylose

Question 3

The denticity of an organic ligand, biuret is :

Accepted Answer

2

Answer

6

Answer

3

Answer

4

Question 4

Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R).Assertion (A) : A simple distillation can be used to separate a mixture of propanol and propanone.Reason (R) : Two liquids with a difference of more than 20ºC in their boiling points can be separated bysimple distillations.In the light of the above statements, choose the most appropriate answer from the options given below :

Accepted Answer

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

Answer

(A) is false but (R) is true

Answer

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

Answer

(A) is true but (R) is false

Question 5

The major component/ ingredient of Portland Cement is :

Accepted Answer

tricalcium silicate

Answer

tricalcium aluminate

Answer

dicalcium silicate

Answer

dicalcium aluminate

Question 6

Given below are two statements : one is labelled as Assertion (A) and the other is labelled as Reason (R).Assertion (A) : Metallic character decreases and non-metallic character increases on moving from leftto right in a period.Reason (R) : It is due to increase in ionisation enthalpy and decrease in electron gain enthalpy, whenone moves from left to right in a period.In the light of the above statements, choose the most appropriate answer from the options givenbelow :

Accepted Answer

(A) is true but (R) is false

Answer

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

Answer

(A) is false but (R) is true

Answer

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

Question 7

Monomer of Novolac is :

Accepted Answer

o-Hydroxymethyl Phenol

Answer

phenol and melamine

Answer

3-Hydroxybutanoic acid

Answer

1,3-Butadiene and styrene

Question 8

Given below are two statements : one is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A): Aluminium is extracted from bauxite by the electrolysis of molten mixture of Al2​O3​ with cryolite.Reason (R) : The oxidation state of Al in cryolite is +3In the light of the above statements, choose the most appropriate answer from the options given below

Accepted Answer

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

Answer

(A) is false but (R) is true

Answer

(A) is true but (R) is false

Answer

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

Question 9

Let the equation of the plane, that passes through the point (1,4,−3) and contains the line of intersection of the planes 3x−2y+4z−7=0 and x+5y−2z+9=0 , be αx+βy+γz+3=0 , that α+β +γ is equal to:

Accepted Answer

-23

Answer

15

Answer

23

Answer

15

Question 10

A uniform heavy rod of weight 10 kg ms−2 , cross-sectional area 100 cm2 and length 20 cm is hanging from a fixed support. Young modulus of the material of the rod is 2×1011Nm−2 . Neglecting the lateral contraction, find the elongation of rod due to its own weight :

Accepted Answer

5×10−10 m

Answer

4×10−8 m

Answer

2×10−9 m

Answer

5×10−8 m

Question 11

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

Accepted Answer

A  17

Answer

A > 50, B < 27

Answer

A > 25, B < 17

Answer

A > 15, B > 47

Question 12

In the structure of the dichromate ion, there is a :

Accepted Answer

non-linear symmetrical Cr–O–Cr bond

Answer

non-linear unsymmetrical Cr–O–Cr bond

Answer

linear unsymmetrical Cr–O–Cr bond

Answer

linear symmetrical Cr–O–Cr bond