rao iit academy / date: 12 jan 2019 jee main official … · 2019-01-19 · rotational motion,...

Rao IIT Academy /JEE MAIN OFFICIAL

ONLINE EXAM / 12January19 Slot I /

Solutions

Date: 12 Jan 2019

Rao IIT Academy Website : www.raoiit.com1

Rao IIT Academy / JEE - MAIN Official / Online Exam / 12 -Jan-19 / Slot - I / Solutions

1.Di�iculty : Medium

Topics :

Gravitation,

By conservation of momentum (along - direction)

..........(1)

Similar, conservation of momentum (along -aixs)

........(2)

Net velocity =

So path will be elliptical.


Topics :

Heat and thermodynamics,

Energy of gas

=

= Joule



3. Di�iculty : Di�icult

Topics :

Current electricity,

Let resistance of galvanometer is

when key is closed & is open

.............(1)

...............(2)

When is closed

..........(3)

...........(4)

...........(5)

By Eqn (3),(4) & (5) we get

............(6)

From Eqn. (2) & (6)



4. Di�iculty : Medium

Topics :

Electromagnetic waves,

Amplitude of electric field

Intensity in air .......(1)

Intensity in medium .......(2)

4% light get reflected so


Topics :

Rotational Motion,

Moment of Inertia of a hollow cylinder is

Now radius of gyration




Topics :

Alternating current,

long time a�er switch is closed, Let current in the circuit is then


Topics :


Thermal resistance

where is the thermal conductivity

Thermal resistance of inner cylinder of radius

.........(1)

Thermal resistance of outer cylinder of radius

...........(2)

.....(3)




Topics :

Geometrical Optics,

Let position of image formed by convex lens is

distance of image from concave lens is

New position of image formed by concave lens

Real image, from concave lens.

9.Di�iculty : Easy

Topics :

Wave Motion,

Travelling wave equation

This equation represent that wave is travelling direction.

Speed of wave




Topics :

Gravitation,

Mass per unit length of the rod is

Gravitational force between point mass and element of mass



11. Di�iculty : Easy

Topics :

Semiconductors,




Topics :

Modern Physics,

Given

In circular motion

Boh'r quantization

from

total energy



13.Di�iculty : Di�icult

Topics :

Simple harmonic motion,

torque about

frequency




Topics :

SOUND,

Let the speed of plane is


Topics :


length of is

given

(Where is a proportional constant)




Topics :

MEASUREMENT,

L.C (of screw gauge)=


Topics :

Magnetic E�ects of Current,

Given (Let). magnetic field at point is magnetic field at pointO due to wire and is zero

= (X) ........(1)

Magnetic field at due to wire is

= ....(2)

Net magnetic field at is

into the page




Topics :

Kinematics,

When they are moving in same direction, relative velocity of train w.r. to train .

Time taken by the train to cross the train

.......(1)

When the trains moving opposite drections

........(2)


Topics :

Communication systems,

Modulation index ............(1)

given maximum amplitude

.............(2)

minimum amplitude

..............(3)

by eqn (2) & (3), we get

&

so




Topics :


Work done by gas = area of triangle

=

=




Topics :

System of particles,

Let velocity of bob at point is when it is released from (before collision)

By conservation of energy at point and

...........(1)

Let velocity of bob a�er the collision is

..........(2)

by conservation of energy at point and

=

.............(3)

By eqn (2) & (3)

=




Topics :


Net resistance

Current in the circuit

Power consumed by bulb

Power consumed by bulb


Topics :


Potential gradient




Topics :

Modern Physics,

potential same and magnetic field same


Topics :

System of particles,

Component of centre of man

Component of centre of Man




Topics :

Electrostatics,

So graph between and is


Topics :

Geometrical Optics,

are similar triangle

So Total distance a over which the man can see the image is




Topics :

Electrostatics,

dipole moment and diraction from to

Net dipole Moment


Topics :

Modern Physics,

De-Broglie wavelength




Topics :

Capacitors,

Charge on capacitor before turned the switch

When switch is turned from to position

Charge will transfered from one capacitor to another capacitor untill potential will not same Let common potential is

Initial energy

Final energy

Energy dissipated

1.

Di�iculty : MediumTopics :Colligative properties,

Note: Here we have taken the given concentration in



CHEMISTRY


Topics :

Gaseous State,

Note: Compressibility factor


Topics :

Volumetric analysis,

Equialent of acid = Equivalent of base

for

Bonus question as no options matches


Topics :

S-block,

Metal form superoxides with excess air which on hydrolysis give and .




Topics :

Chemical Kinetics,

Unit of rate constant is as per zero order.

For zero order rate constant


Topics :

Alcohols,

As mechanism is nucleophilic addition where alcohol acts as nucleophile where carbonyl carbon is acts as electrophilliccenter. Formaldehyde is more reactive fast attack by small size of alcohol methanol.


Topics :

BIOMOLECULES ,

Lysine is most basic amino acid amongst given amino acids.


Topics :

Surface Chemistry,

Higher the value of , easier will be its liquification and higher will be its absorbant ability or rate.



9 .Di�iculty : Medium

Topics :

GOC,

M.P. Intermolecular forces

Naphthalane has weak intermolecular force amongst given option


Topics :

Reduction,


Topics :

Electrochemistry,

{ Divided by 1000 to find answer in KJ}




Topics :

Atomic Structure,

( is the work function)

approximately.


Topics :

GOC,


Topics :

Coordination Compounds,

is a strong ligand so forms low spin inner orbital complex.




Topics :


is a weak ligand so form high spin outer orbital complex.


Topics :

Metallurgy,

In Hall- Heroull's process

Cathode is made up of Carbon/Graphite so that it can convert fused to .


Topics :

P-block-I,

gives Iodic Acid with conc. reaching oxidation state +5.




Topics :

Volumetric analysis,

Eq. of in 1 litre = Eq. of in 1 litre

Milli equivalents = 2

Milli moles = 1

Milli grams of per litre


Topics :

Environmental Chemistry,

If (safe water)

(clean)

(highly polluted)


Topics :

Chemical equilibrium,

[ is common in both reaction]

total pressure




Topics :

Chemical equilibrium,

at equilibrium,

Equilibrium constant


Topics :

Aromatic compounds,


Topics :

CARBONYLS,

Note: Intramolecular aldol condensation.




Topics :

Thermodynamics,

As molar heat capacities, and are both function of temperature

Graph (3) is wrong as remains same on changing pressure but varies on changing temperature.


Topics :

Environmental Chemistry,

is not involved in formation of photochemical smog as it's non combustible & has very high dissociation enthalpy


Topics :

Grignards reagent,


Topics :

Periodic Table,

Group IIA or 2 (Alkaline Earth Metal)



28. Di�iculty : Di�icult

Topics :

Polymers,

is copolymer of 3-hydroxybutanoic acid and 3-hydroxypentanoic acid


Topics :


Organometallic due to metal-carbon bond

is a metal carbon bond.


Topics :

Alkyl halides,

Reactivity order toward



1.

Di�iculty : Medium

Topics :

Three Dimensional Geometry,

normal vector of face OPQ

normal vector of face PQR


Topics :

Area under curve,



MATHEMATICS


Topics :

Mathematical reasoning,


Topics :

Quadratic Equations,




Topics :

Matrices Multiplications,


Topics :

Straight lines,




Topics :

Hyperbola,

will not satisfy.


Topics :

Sequence & Series,




Topics :

Definite integrals,


Topics :

Inverse Trigonometric Functions,

A is a singleton set




Topics :

Di�erentiation,

is not di�erentiale

Subject of


Topics :

Di�erentiation,

At




Topics :

Circles,

(1,1) and (9,1) are on opposite side of line

Radius of circle should be smaller than perpendicular distance from centre on line


Topics :

Limits,




Topics :

Circles,

Two circles are intersecting orthogonally


Topics :

Parabola,

Area will be maximum when tangent at is parallel to




Topics :

STATISTICS,


Topics :

Permutations & Combinations,

Product of elements is even when atleast one even number is present

Total subsets - (No. even no. is present)


Topics :

PERMUTATION AND COMBINATION,

If any three balls are chosen by then we can assign smallest numbered ball to box and go on.




Topics :

Di�erentiation,


Topics :

Application of derivatives,




Topics :

TRIGONOMETRY,


Topics :

Binomial Theorem,




Topics :

Sequence & Series,


Topics :

Vectors,




Topics :

Complex Numbers,


Topics :

Indefinite integration,

Integration by parts


Topics :

Probability,




Topics :

Determinants,


Topics :

Three Dimensional Geometry,



rao iit academy / date: 12 jan 2019 jee main official … · 2019-01-19 · rotational motion,...

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