Practice problems on JEE Mains, JEE Mains 2021 Mar 18 Shift 1

Question 1

Match List-I with List-II

Accepted Answer

(a)–(ii), (b)–(iv), (C)–(i), (D)–(iii)

Answer

(a)–(i), (b)–(iii), (C)–(ii), (D)–(iv)

Answer

(a)–(iv), (b)–(ii), (C)–(i), (D)–(iii)

Answer

(a)–(iii), (b)–(i), (C)–(iv), (D)–(ii)

Question 2

The number of integral values of m so that the abscissa of point of intersection of lines 3x + 4y = 9 and y = mx + 1 is also an integer, is :

Accepted Answer

2

Answer

1

Answer

3

Answer

0

Question 3

Match List-I with List-II :

Accepted Answer

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

Answer

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

Answer

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

Answer

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

Question 4

If limx→0​3x3sin−1x−tan−1x​ is equal to L, then the value of (6L + 1) is :

Accepted Answer

2

Answer

1/6

Answer

6

Answer

1/2

Question 5

Match List-I with List-II

Accepted Answer

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

Answer

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

Answer

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

Answer

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

Question 6

A radioactive sample disintegrates via two independent decay processes having half lives T1/2(1)​ and T1/2(2)​ respectively. The effective half-life, T1/2​ of the nuclei is :

Accepted Answer

T1/2​=T1/2(1)​+T1/2(2)​T1/2(1)​T1/2(2)​​

Answer

T1/2​=T1/2(1)​−T1/2(2)​T1/2(1)​T1/2(2)​​

Answer

T1/2​=T1/2(1)​+T1/2(2)​

Answer

None of the above

Question 7

A non-reducing sugar "A" hydrolyses to give two reducing monosaccharides. Sugar A is:

Accepted Answer

Sucrose

Answer

Galactose

Answer

Glucose

Answer

Fructose

Question 8

Given below are two Statements: One is labelled as Assertion A and the other is labelled as Reason R: Assertion A : During the boiling of water having temporary hardness, Mg(HCO3​)2​ is converted to MgCO3​ . Reason R: The solubility product of Mg(OH)2​ is greater than that of MgCO3​.In the light of the above statements, choose the most appropriate answer from the options given below:

Accepted Answer

A is false but R is true

Answer

Both A and R are true and R is the correct explanation of A

Answer

Both A and R are true and R is NOT the correct explanation of A

Answer

A is true but R is false

Question 9

In a series LCR resonance circuit, if we change the resistance only, from a lower to higher value :

Accepted Answer

The bandwidth of resonance circuit will increase

Answer

The quality factor will increase

Answer

The resonance frequency will increase

Answer

The quality factor and the resonance frequency will remain constant

Question 10

Let (1+x+2x2)20=a0​+a1​x+a2​x2+……+a40​x40. Then, a1​+a3​+a5​+….+a37​ is equal to :

Accepted Answer

219(220−21)

Answer

219(220+21)

Answer

220(220−21)

Answer

220(220+21)

Question 11

Reagent, 1-naphthylamine and sulphanilic acid in acetic acid is used for the detection of:

Accepted Answer

NO2−​

Answer

NO3−​

Answer

N2​O

Answer

NO

Question 12

The ionic radius of Na+ion is 1.02A˚. The ionic radii (in A˚ ) of Mg2+ and Al3+ , respectively, are:

Accepted Answer

0.72 and 0.54

Answer

0.68 and 0.72

Answer

1.05 and 0.99

Answer

0.85 and 0.99

Question 13

The equation of one of the straight lines which passes through the point (1,3) and makes an angle tan−1(2​) with the straight line, y+1=32​x is :

Accepted Answer

42​x+5y−(15+42​)=0

Answer

42​x−5y−(5+42​)=0

Answer

42​x+5y−42​=0

Answer

52​x+4y−(15+42​)=0