Recent questions and answers in JEEMAIN-2014

How many electrons are involved in the following redox reaction ? $\;Cr_{2}O_{7}^{2-}+Fe^{2+}+Cr_{2}O_{4}^{2-} \to Cr^{3+} + Fe^{3+} + CO_{2}\;$ (unbalanced)

answered Jan 31, 2021 by abdulrahimshafiuyusuf

1 answer

A hot body , obeying Newton's law of cooling is cooling down from its peak value $\;80^{0}C\;$to an ambient temperature of $\;30^{0}C\;$ . It takes 5 minutes in cooling down from $\;80^{0}C\;$ to $\;40^{0}C\;$. How much time will it take to cool down from $\;62^{0}C\;$ to $\;32^{0}C\;$ ? (Given ln 2=0.693 ; ln 5=1.609)

answered Jan 30, 2021 by akankshyanayak620

1 answer

The angular frequency of the damped oscillator is given by , $\;w=\sqrt{\large\frac{k}{m}-\large\frac{r^{2}}{4m^{2}}}\;$ where k is the spring constant , m is the mass of the oscillator and r is the damping constant.If the ratio $\;\large\frac{r^{2}}{mk}\;$ is $\;8\%\;$ , the change in time period compared to the undamped oscillator is approximately as follows :

answered Aug 9, 2020 by perilioustanmay

1 answer

Which of the following arrangements represents the increasing order (smallest to largest) of ionic radii of the given species $\;O^{2-} ,S^{2-} ,N^{3-} ,P^{3-}\;$ ?

answered Jul 16, 2020 by aakarshnair17

1 answer

If m and e are the mass and charge of the revolving electron in the orbit of radius r for hydrogen atom , the total energy of the revolving electron will be :

answered Apr 8, 2020 by aaryanandavadekar123

1 answer

The variance of first 50 even natural numbers is :

answered Feb 6, 2020 by laxmikntpanda25

1 answer

A particle is moving in a circular path of radius a , with a constant velocity v as shown in the figure . The center of circle is marked by 'C' .The angular momentum from the origin O can be written as :

answered Jan 7, 2020 by pady_1

1 answer

A transmitting antenna at the top of a tower has a height 32 m and the height of the receiving antenna is 50 m .What is the maximum distance between them for satisfactory communication in line of sight (LOS) mode ?

answered Dec 20, 2019 by swapnarajan1982

2 answers

Which of the following statements about the depletion of zone layer is correct ?

answered Dec 12, 2019 by mallaanandsai

1 answer

Van der waal's equation for a gas is stated as , $\;p=\large\frac{nRT}{V-nb}- a(\large\frac{n}{v})^{2}\;$ .This equation reduces to the perfect gas equation $\;p=\large\frac{nRT}{V}\;$ when ,

answered Nov 10, 2019 by pcsaini9460

1 answer

If Z is a compressibility factor ,van der waals equation at low pressure can be written as :

answered Nov 10, 2019 by pcsaini9460

1 answer

The initial volume of a gas cylinder is 750.0 mL . If the pressure of gas inside the cylinder changes from 840.0 mm Hg to 360.0 mm Hg , the final volume the gas will be :

answered Sep 24, 2019 by rinkunishan

1 answer

Which one of the following molecules is paramagnetic ?

answered Sep 2, 2019 by dhruvmiyani66

1 answer

A block A of mass 4 kg is placed on another block B of mass 5 kg , and the block B rests on a smooth horizontal table . If the minimum force that can be applied on A so that both the blocks move together is 12 N , the maximum force that can be applied on B for the blocks to move together will be :

answered Aug 16, 2019 by meena.clay6

1 answer

From the following combinations of physical constants (expressed through their usual symbols) the only combination , that would have the same value in different systems of units , is :

answered Jul 25, 2019 by saurav.beg987

1 answer

An experiment is performed to obtain the value of acceleration due to gravity g by using a simple pendulum of length L .In this experiment time for 100 oscillations is measured by using a watch of 1 second least count and the value is 90.0 seconds .The length L is measured by using a meter scale of least count 1 mm and the value is 20.0 cm.The error in the determination of g would be :

answered Jul 17, 2019 by anshuldarediya007

1 answer

If [] denotes the greatest integer function , then the integral $\;\int \limits_{0}^{\pi} [cos x] dx\;$ is equal to :

answered Jul 12, 2019 by poonamgaur98

1 answer

Which of the following has unpaired electron(s) ?

answered Jul 11, 2019 by kaushikkarthikeyan2511.kk

1 answer

A piece of wood from a recently cut tree shows 20 decays per minute .A wooden piece of same size placed in a museum (obtained from a tree cut many years back) show 2 decays per minute .If half life of $\;C^{14}\;$ is 5730 years , then age of the wooden piece placed in the museum is approximately :

answered Jul 1, 2019 by habtamugeta27

1 answer

Two ships A and B are sailing straight away from a fixed point O along routes such that $\;\angle{AOB}\;$ is always $\;120^{0}\;$ . At a certain distance , OA=8 km ,OB=6 km and the ship A is sailing at the rate of 20 km/hr while the ship B sailing at the rate of 30 km/hr . Then the distance between A and B is changing at the rate ( in km/hr ) :

answered Jun 30, 2019 by yadavdheeraj518

1 answer

For which of the following particles will it be most difficult to experimentally verify the de-Broglie relationship ?

answered Jun 25, 2019 by deepaktomar51208

1 answer

The sum of the roots of the equation ,$\;x^{2}+|2x-3|-4=0\;$ is :

answered Jun 23, 2019 by monishkrishnan619

1 answer

Which one of the following ores is known as Malachite :

answered Jun 11, 2019 by priyaranjani437

1 answer

Which one of the following complexes will most likely absorb visible light ? (At nos. Sc=21,Ti=22,V=23,Zn=30)

answered Apr 27, 2019 by kandoihanish

1 answer

For all complex numbers z of the form $\;1+i \alpha\;, \alpha \in R\;$ , if $\;z^{2}=x+iy\;$ , then :

answered Apr 20, 2019 by shrihari689

1 answer

India's mangalyan was sent to the mars by launching it into a transfer orbit EOM around the sun .It leaves the earth at E and meets mars at M.If the semi - major axis of earth's orbit is $\;a_{e}=1.5 \times 10^{11} m\;$ , that of Mar's orbit $\;a_{m}=2.28 \times 10^{11} m\;$, taken Kepler's law give the estimate of time for mangalyan to reach Mars from Earth to be close to :

answered Apr 4, 2019 by hareshkumar749

1 answer

Which one of the following does not have a pyramidal shape ?

answered Mar 28, 2019 by sharmaaparna1

1 answer

The correct statement about the magnetic properties of $\;[Fe(CN)_{6}]^{3-}\;$ and $\;[FeF_{6}]^{3-}\;$ is : (Z=26)

answered Mar 23, 2019 by hanumantinda

1 answer

A bob of mass m attached to an inextensible string of length / is suspended from a vertical support . The bob rotates in a horizontal circle with an angular speed $\;w\;$ rad/s about the verticle . About the point of suspension :

answered Mar 22, 2019 by ainaraichal

1 answer

For the two circles $\;x^{2}+y^{2}=16\;$ and $\;x^{2}+y^{2}-2y=0\;$ , there is/are :

answered Mar 22, 2019 by somdatt.pandhare

1 answer

Aminoglycosides are usually used as :

answered Mar 22, 2019 by somdatt.pandhare

1 answer

Zirconium phosphate $\;[Zr_{3}(PO_{4})_{4}]\;$ dissociates into three zirconium cations of charge +4 and four phosphate anions of charge -3 . If molar solubility of zirconium phosphate is denoted by S and its solubility product by $\;K_{sp}\;$ then which of the following relationship between $\;S\;$ and $\;K_{sp}\;$ is correct ?

answered Mar 17, 2019 by urviagarwal2002

1 answer

In the circuit shown , current (in A) through the 50 V and 30 V batteries are , respectively :

answered Mar 8, 2019 by ankushshekhawat123

1 answer

Four bulbs $\;B_{1},B_{2},B_{3}\;$ and $\;B_{4}\;$ of 100 W each are connected to 220 V main as shown in the figure .The reading in an ideal ammeter will be :

answered Jan 5, 2019 by chiranjeevi.ta

1 answer

At room temperature a diatomic gas is found to have an r.m.s. speed of $\;1930\;ms^{-1}\;$ .The gas is :

answered Jan 2, 2019 by shubh.2001.k

1 answer

A current of 10.0 A flows for 2.00 h through an electrolytic cell containing a molten salt of metal X . This results in the decomposition of 0.250 mol of metal X at the cathode . The oxidation state of X in the molten salt is : (F=96,500 C)

answered Dec 30, 2018 by lakshmanarao.sasanala

1 answer

A transverse wave is represented by : $\;y=\large\frac{10}{\pi} sin (\large\frac{2 \pi}{T} t - \large\frac{2 \pi}{\lambda} x)\;$ . For what value of the wavelength the wave velocity is twice the maximum particle velocity ?

answered Dec 29, 2018 by anidatar2

1 answer

Complete reduction of benzene - diazonium chloride with $\;Zn/HCI\;$ gives :

answered Dec 21, 2018 by somisettysrinu1

1 answer

Two hypothetical plates masses $\;m_{1}\;$ and $\;m_{2}\;$ are at rest when they are infinite distance apart .Because of the gravitational force they move towards each other along the line joining their centers .What is their speed when their separation is 'd ' ? (Speed of $\;m_{1}\;$ is $\;v_{1}\;$ and that of $\;m_{2}\;$ is $\;v_{2}\;$)

answered Dec 21, 2018 by ajaynath630

1 answer

A spherically symmetric charge distribution is characterised by a charge density having the following variation : \[\]$\;\rho(r)=\rho_{0}(1-\large\frac{r}{R})\;for\;r < \normalsize R\;$\[\]$\;\rho(r) =0 \;\; r \geq R\;$ \[\] where r is the distance from the center of the charge distribution and $\;\rho_{0}\;$ is a constant .The electric field at an internal point $(r < R)$ is :

answered Dec 20, 2018 by ymisaurav

1 answer

If the binding energy of the electron in a hydrogen atom is 13.6 eV , the energy required to remove the electron from the first exited state of $\;Li^{++}\;$ is :

answered Dec 16, 2018 by skumarmishra799

1 answer

If $\;cosec\theta = \large\frac{p+q}{p-q}\;(p \neq q \neq 0)\;$, then $\;|cot(\large\frac{\pi}{4} + \large\frac{\theta}{2})|\;$ is equal to :

answered Dec 12, 2018 by prachijaiswal438

1 answer

The locus of the foot of perpendicular drawn from the centre of the ellipse $\;x^{2}+3y^{2}=6\;$ on any tangent to it is :

answered Dec 9, 2018 by devchahwala2001

1 answer

An ideal monoatomic gas is confined in a cylinder by a spring loaded piston of cross section $\;8.0 \times 10^{-3}\;m^{2}\;$.Initially the gas is at 300K and occupies a volume of $\;2.4\times10^{-3}\;m^{3}\;$ and the spring is in its relaxed state as shown in figure.The gas is heated by a small heater until the piston moves out slowly by 0.1 m .The force constant of the spring is 800 N/m and the atmospheric pressure is $\;1.0 \times 10^{5}\;N/m^{2}\;$ . The cylinder and the piston are thermally insulated .The piston and the spring are massless and there is no friction between the piston and the cylinder .The final temperature gas will be : (Neglect the heat loss through the lead wires of the heater.The heat capacity of the heater coil is also negligible)

answered Dec 7, 2018 by saru.d.gr8

1 answer

A square frame of side 10 cm along straight wire carrying current 1 A are in the plane of the paper . Starting from close to the wire , the frame moves towards the right with a constant speed of $\;10\;ms^{-1}\;$ (see figure) .The e.m.f. induced at the time the left arm of the frame is at x=10 cm from the wire is :

answered Dec 7, 2018 by faraz246.hassan

1 answer

Which one of the following reactions will not result in the formation of carbon - carbon bond :

answered Dec 5, 2018 by phuntsogwangail10

1 answer

Which one of the following xenon - OXO compounds may not be obtained by hydrolysis of xenon fluorides ?

answered Nov 23, 2018 by cartooonboooy

1 answer

The least positive integer n such that $\;1-\large\frac{2}{3} -\large\frac{2}{3^{2}}- ..... -\large\frac{2}{3^{n-1}} < \large\frac{1}{100}\;$, is :

answered Nov 22, 2018 by rpukvpy

1 answer

The total number of octahedral void(s) per atom present in a cubic close packed structure is :

answered Nov 20, 2018 by vetribalajipress

1 answer

The current voltage relation of diode is given by $\;(I=e^{\large\frac{1000V}{T}-1})mA\;$ , where the applied voltage V is in volts and the temperature T is in degree kelvin .If a student makes an error measuring $\;\pm0.001 V\;$ while measuring the current of 5 mA at 300 K , what will be the error in the value of current in mA ?

answered Nov 16, 2018 by abhijitbarde1002

1 answer

Ask Questions, Get Answers