#jeemainmarch2021

17 questions

The radius in kilometer to which the present radius of earth (R = 6400 km) Correct answer is 64 km Explanation:: Physics 1 answer
The radius in kilometre to which the present radius of earth (R = 6400 km) to be compressed so that the escape velocity is increased 10 times is ____________ 64 km solution:: Escape velocity = √(2GMover R) we know mass remain unchanged V_e' over V_e = √(R_eover R_e') 10Vover eover Vover e =√(6400o... Physics 1 answer
A Carnot's engine working between 400 K and 800 K has a work output of 1200 J per cycle. (2) 2400 J Explaination:: Wover Q_in=1-T₂over T₁=1-1over2=1over2 1200over Q_in=1over2 Q_in=2400 J Physics 1 answer
A polyatomic ideal gas has 24 vibrational modes. What is the value of gamma ? (2) 1.03 is the correct option Explaination :: f= 3+3 +24 (vibrational modes) =30 γ = 1+2over30=16over15 γ=1.067 Physics 2 answers
Which level of the single ionized carbon has the same energy as the ground state energy of hydrogen atom ? Correct answer is option (1) 6 Physics 2 answers
The output of the given combination gates represents : 2) Nand gate is the correct answer Physics 1 answer
For what value of displacement the kinetic energy and potential of a simple harmonic oscillation become equal ? The correct option is (3) x= ±Aoversqrt2 Explaination:: potential energy = 1over2kx²=1over2mω²( x²) Kinetic energy = 1over2m(ω√( A²-x²))² As... Physics 1 answer
A certain element crystallises in a bcc lattice of unit cell edge, length 27ºÅ. If the same element Answer: 33 Explanation:: for bcc structure 4r=sqrt3a r=sqrt3aover4 …1 For FCC structure 4r=sqrt2a r=sqrt2aover4 …2 From 1 and 2 Random 1 answer
Which of the following reaction DOES NOT involve Hoffmann bromamide degradation ? The correct answer is option 3) This reaction does not involve haffmann bromanide degradation Rest all options involve haffmann bromamide de... Random 1 answer
The process that involves the removal of sulphur from the ores is : jee main march 2021 1) roasting Removal of sulphur from the ore is done by Roasting. Random 1 answer
Which among the following pairs of Vitamins is stored in our body relatively for longer duration ? (2) Vitamin A and Vitamin D Random 2 answers
In chromatography technique, the purification of compound is independent of : Correct answer is option (2) Physical state of the pure compound In chromotography technique, the purification of a compound is independent... Random 1 answer
Which of the following is Lindlar catalyst ? (1) Cold dilute solution of KMnO4 (2) Partially deactivated palladised charcoal Random 2 answers
A group 15 element, which is a metal and forms a hydride with strongest reducing power among group 15 hydrides. The correct answer is option 2 ) Bi Random 2 answers
In thermodynamics, heat and work are : (1) Extensive thermodynamic state variables (2) Point functions (3) Path functions The correct answer is option 3) path function Physics 2 answers
A 25 m long, antenna is mounted on an antenna tower. The height of the antenna tower is 75 m. The correct answer is option 3) 100 m Explanation: height of antenna= λover 4 25= λover 4 λ=100 Physics 1 answer
The maximum and minimum distances of comet from the Sun are 1.6 × 1012 m and 8.0 × 1010 m respectively The correct answer is option A) 3.0×10³ m/s Explanation:: L=mv₁r₁=mv₂r₂ V₂= v₁r₁over r₂ =v₁ 8×10¹⁰over 160×10¹⁰ =6×10⁴over 20 =3000 m/s Physics 1 answer