List of top Questions asked in JEE Main- 2019

An insulating thin rod of length $\ell$ has a x linear charge density $p(x) = \rho_0 \frac{x}{\ell}$ on it . The rod is rotated about an axis passing through the origin $(x = 0)$ and perpendicular to the rod. If the rod makes n rotations per second, then the time averaged magnetic moment of the rod is :

The figure shows a square loop $L$ of side $5\, cm$ which is connected to a network of resistances. The whole setup is moving towards right with a constant speed of $1\, cms^{-1}$. At some instant, a part of $L$ is in a uniform magnetic field of $1T$, perpendicular to the plane of the loop. If the resistance of $L$ is $1.7\, \Omega$ , the current in the loop at that instant will be close to :

A simple pendulum, made of a string of length $l$ and a bob of mass m, is released from a small angle $\theta_0$. It strikes a block of mass $M$, kept on a horizontal surface at its lowest point of oscillations, elastically. It bounces back and goes up to an angle $\theta_1$. Then M is given by :

A simple pendulum of length $1\, m$ is oscillating with an angular frequency $10\, rad/s$. The support of the pendulum starts oscillating up and down with a small angular frequency of $1 \,rad/s$ and an amplitude of $10^{-2} \; m$. The relative change in the angular frequency of the pendulum is best given by :

A block of mass $m$, lying on a smooth horizontal surface, is attached to a spring (of negligible mass) of spring constant $k$. The other end of the spring is fixed, as shown in the figure. The block is initally at rest in its equilibrium position. If now the block is pulled with a constant force $F$, the maximum speed of the block is :

A force acts on a $2\, kg$ object so that its position is given as a function of time as $x = 3t^2 + 5$. What is the work done by this force in first $5$ seconds ?

A man (mass = $50\, kg$) and his son (mass = $20\, kg$) are standing on a frictionless surface facing each other. The man pushes his son so that he starts moving at a speed of $0.70\, ms^{-1}$ with respect to the man. The speed of the man with respect to the surface is :

A piece of wood of mass $0.03\, kg$ is dropped from the top of a $100 \,m$ height building. At the same time, a bullet of mass $0.02\, kg$ is fired vertically upward, with a velocity $100 \; ms^{-1}$, from the ground. The bullet gets embedded in the wood. Then the maximum height to which the combined system reaches above the top of the building before falling below is : $(g =10\,ms^{-2})$

A spring whose unstretched length is $l$ has a force constant $k$. The spring is cut into two pieces of unstretched lengths $l_1$ and $l_2$ where, $l_1$ = $nl_2$ and $n$ is an integer. The ratio $k_1/k_2$ of the corresponding force constants, $k_1$ and $k_2$ will be :

A uniform cable of mass $'M'$ and length $'L'$ is placed on a horizontal surface such that its $\bigg(\frac{1}{n}\bigg)^{th}$ part is hanging below the edge of the surface. To lift the hanging part of the cable upto the surface, the work done should be :

An alpha-particle of mass m suffers 1-dimensional elastic coolision with a nucleus at rest of unknown mass. It is scattered directly backwards losing, $64\%$ of its initial kinetic energy. The mass of the nucleus is :

A string of length $1\, m$ and mass $5\, g$ is fixed at both ends. The tension in the string is $8.0\, N$. The siring is set into vibration using an external vibrator of frequency $100\, Hz$. The separation between successive nodes on the string is close to :

A travelling harmonic wave is represented by the equation $y (x, t) = 10^{-3} sin (50 t + 2x)$, where $x$ and $y$ are in meter and $t$ is in seconds. Which of the following is a correct statement about the wave? The wave is propagating along the

A tuning fork of frequency $480\, Hz$ is used in an experiment for measuring speed of sound (n) in air by resonance tube method. Resonance is observed to occur at two successive lengths of the air column, $l_1$ = 30 cm and $l_2$ = $70 \,cm$. Then, $v$ is equal to :

Equation of travelling wave on a stretched string of linear density $5\, g/m$ is $y\, =\, 0.03\, sin(450\, t - 9x)$ where distance and time are measured is SI units. The tension in the string is :

The IUPAC symbol for the element with atomic number $119$ would be :

Two identical spherical balls of mass $M$ and radius $R$ each are stuck on two ends of a rod of length $2R$ and mass $M$ (see figure). The moment of inertia of the system about the axis passing perpendicularly through the centre of the rod is :

The correct decreasing order for acid strength is :

The correct order of hydration enthalpies of alkali metal ions is -

A solution containing $62\, g$ ethylene glycol in $250 \,g$ water is cooled to $-10^{\circ}C$. If $K_f$ for water is $1.86\, K\, kg \,mol^{-1}$, the amount of water (in g) separated as ice is :

The effect of lanthanoid contraction in the lanthanoid series of elements by and large means :

When $M_1$ gram of ice at $-10^{\circ}C$ (specific heat = $0.5 \; cal \; g^{-1 \circ } C^{-1}$) is added to $M_2$ gram of water at $50^{\circ}C$, finally no ice is left and the water is at $0^{\circ}C$. The value of latent heat of ice, in cal $g^{-1}$ is:

The mean and the median of the following ten numbers in increasing order $10, 22, 26, 29, 34, x 42, 67, 70,\, y$ are $42$ and $35$ respectively, then $\frac{y}{x}$ is equal to :

A particle starts from origin $O$ from rest and moves with a uniform acceleration along the positive $x$-axis. Identify all figures that correctly represent the motion qualitatively. (a = acceleration, v = velocity, x = displacement, t = time)

A circular disc $D_1$ of mass $M$ and radius $R$ has two identical discs $D_2$ and $D_3$ of the same mass $M$ and radius $R$ attached rigidly at its opposite ends (see figure). The moment of inertia of the system about the axis $OO'$, passing through the centre of $D_1$, as shown in the figure, will be :