Recent questions in JEEMAIN PAST PAPERS

If the sum of the first ten terms of the series $(1 + \frac{3}{5})^2 + ( 2 + \frac{2}{5})^2 + (3 + \frac{1}{5})^2 + 4^2 + (4 + \frac{4}{5})^2......,$ is $\frac{16}{5} m$, then $m$ is equal to :

asked Dec 11, 2018 by pady_1

1 answer

If the $2^{nd},\; 5^{th}$ and $9^{th}$ terms of a non-constant A.P. are in G.P., then the common ratio of this G.P. is :

asked Dec 11, 2018 by pady_1

1 answer

If the number of terms in the expansion of $\begin{pmatrix} 1 - \frac{2}{x} + \frac{4}{x^2} \end{pmatrix}^n, x \neq 0$ is 28, then the sum of the coefficients of all the terms in this expansion, is :

asked Dec 11, 2018 by pady_1

1 answer

If all the words (with or without meaning) having five letters, formed using the letters of the word SMALL and arranged as in a dictionary; then the position of the word SMALL is :

asked Dec 11, 2018 by pady_1

1 answer

The system of linear equations $ x + \lambda y - z = 0 $ $\lambda x - y - z =0$ $x + y - \lambda z = 0$ has a non-trivial solution for :

asked Dec 11, 2018 by pady_1

1 answer

If $A= \begin{bmatrix} 5a & -b \\ 3 & 2 \end{bmatrix}$ and $A \; adj \; A = A A^T$, then $5a + b$ is equal to :

asked Dec 11, 2018 by pady_1

1 answer

The sum of all real values of $x$ satisfying the equation $(x^2 - 5x + 5)^{x^2 + 4x - 60} = 1$ is :

asked Dec 11, 2018 by pady_1

1 answer

A value of $\theta$ for which $\frac{2 + 3 i \sin \theta}{1 - 2 i \sin \theta}$ is purely imaginary, is :

asked Dec 11, 2018 by pady_1

1 answer

If $f(x) + 2f (\frac{1}{x}) = 3x, \; x \neq 0$, and $S = \{ x \in R : f(x) = f(-x) \}$; then $S$ :

asked Dec 11, 2018 by pady_1

1 answer

The hottest region of Bunsen flame shown in the figure below is :

asked Dec 11, 2018 by pady_1

0 answers

Which of the following is an anionic detergent ?

asked Dec 11, 2018 by pady_1

1 answer

Thiol group is present in :

asked Dec 11, 2018 by pady_1

0 answers

Which of the following statements about low density polythene is FALSE ?

asked Dec 11, 2018 by pady_1

0 answers

In the Hofmann bromamide degradation reaction, the number of moles of $NaOH$ and $Br_2$ used per mole of amine produced are :

asked Dec 11, 2018 by pady_1

0 answers

The reaction of propene with $HOCl\; (Cl_2+H_2O)$ proceeds through the intermediate :

asked Dec 11, 2018 by pady_1

0 answers

2-chloro-2-methylpentane on reaction with sodium methoxide in methanol yields :

asked Dec 11, 2018 by pady_1

0 answers

The absolute configuration of is :

asked Dec 11, 2018 by pady_1

0 answers

The product of the reaction given below is :

asked Dec 11, 2018 by pady_1

0 answers

The distillation technique most suited for separating glycerol from spent-lye in the soap industry is :

asked Dec 11, 2018 by pady_1

0 answers

The concentration of fluoride, lead, nitrate and iron in a water sample from an underground lake was found to be 1000 ppb, 40 ppb, 100 ppm and 0.2 ppm, respectively. This water is unsuitable for drinking due to high concentration of :

asked Dec 11, 2018 by pady_1

1 answer

Which one of the following complexes shows optical isomerism ? (en=ethylenediamine)

asked Dec 11, 2018 by pady_1

0 answers

The pair having the same magnetic moment is : [At. No : Cr = 24, Mn = 25, Fe = 26, Co = 27]

asked Dec 11, 2018 by pady_1

0 answers

Which of the following compounds is metallic and ferromagnetic ?

asked Dec 11, 2018 by pady_1

0 answers

The pair in which phosphorous atoms have a formal oxidation state of +3 is :

asked Dec 11, 2018 by pady_1

0 answers

The reaction of zinc with dilute and concentrated nitric acid, respectively, produces :

asked Dec 11, 2018 by pady_1

0 answers

The main oxides formed on combustion of Li, Na and K in excess of air are, respectively :

asked Dec 11, 2018 by pady_1

0 answers

Which one of the following statements about water is FALSE ?

asked Dec 11, 2018 by pady_1

0 answers

Which one of the following ores is best concentrated by froth floatation method ?

asked Dec 11, 2018 by pady_1

0 answers

Which of the following atoms has the highest first ionization energy ?

asked Dec 11, 2018 by pady_1

0 answers

For a linear plot of $\log (x/m)$ versus $\log p$ in a Freundlich adsorption isotherm, which of the following statements is correct ? ($k$ and $n$ are constants)

asked Dec 11, 2018 by pady_1

0 answers

Decomposition of $H_2O_2$ follows a first order reaction. In fifty minutes the concentration of $H_2O_2$ decreases from $0.5$ to $0.125\; M$ in one such decomposition. When the concentration of $H_2O_2$ reaches $0.05\; M$, the rate of formation of $O_2$ will be :

asked Dec 11, 2018 by pady_1

0 answers

Galvanization is applying a coating of :

asked Dec 11, 2018 by pady_1

0 answers

The equilibrium constant at $298 \;K$ for a reaction $A+B⇌C+D$ is $100$. If the initial concentration of all the four species were $1\; M$ each, then equilibrium concentration of D (in $mol\; L^{−1}$ ) will be :

asked Dec 11, 2018 by pady_1

0 answers

$18\; g$ glucose $(C_6H_{12}O_6 )$ is added to $178.2\; g$ water. The vapor pressure of water (in torr) for this aqueous solution is :

asked Dec 11, 2018 by pady_1

0 answers

The heats of combustion of carbon and carbon monoxide are $−393.5$ and $−283.5\; kJ \;mol^{−1}$ , respectively. The heat of formation (in kJ) of carbon monoxide per mole is :

asked Dec 11, 2018 by pady_1

0 answers

The species in which the N atom is in a state of sp hybridization is :

asked Dec 11, 2018 by pady_1

0 answers

A stream of electrons from a heated filament was passed between two charged plates kept at a potential difference $V$ esu. If $e$ and $m$ are charge and mass of an electron, respectively, then the value of $h/ \lambda$ (where $\lambda$ is wavelength associated with electron wave) is given by :

asked Dec 11, 2018 by pady_1

0 answers

Two closed bulbs of equal volume $(V)$ containing an ideal gas initially at pressure pi and temperature $T_1$ are connected through a narrow tube of negligible volume as shown in the figure below. The temperature of one of the bulbs is then raised to $T_2$ . The final pressure $p_f$ is :

asked Dec 11, 2018 by pady_1

0 answers

At $300\; K$ and $1 \;atm$, $15\; mL$ of a gaseous hydrocarbon requires $375\; mL$ air containing $20\%\; O_2$ by volume for complete combustion. After combustion the gases occupy $330\; mL$. Assuming that the water formed is in liquid form and the volumes were measured at the same temperature and pressure, the formula of the hydrocarbon is :

asked Dec 11, 2018 by pady_1

0 answers

For a common emitter configuration, if $\alpha$ and $\beta$ have their usual meanings, the incorrect relationship between $\alpha$ and $\beta$ is

asked Dec 11, 2018 by pady_1

0 answers

Identify the semiconductor devices whose characteristics are given below, in the order (a), (b), (c), (d) :

asked Dec 11, 2018 by pady_1

0 answers

In an experiment for determination of refractive index of glass of a prism by $i− \delta$, plot, it was found that a ray incident at angle $35^{\circ}$, suffers a deviation of $40^{\circ}$ and that it emerges at angle $79^{\circ}$ ⋅ Ιn that case which of the following is closest to the maximum possible value of the refractive index ?

asked Dec 11, 2018 by pady_1

0 answers

A galvanometer having a coil resistance of $100 \Omega$ gives a full scale deflection, when a current of $1\; mA$ is passed through it. The value of the resistance, which can convert this galvanometer into ammeter giving a full scale deflection for a current of $10\; A$, is :

asked Dec 11, 2018 by pady_1

0 answers

A pipe open at both ends has a fundamental frequency f in air. The pipe is dipped vertically in water so that half of it is in water. The fundamental frequency of the air column is now :

asked Dec 11, 2018 by pady_1

0 answers

A screw gauge with a pitch of $0.5\; mm$ and a circular scale with $50$ divisions is used to measure the thickness of a thin sheet of Aluminium. Before starting the measurement, it is found that when the two jaws of the screw gauge are brought in contact, the 45th division coincides with the main scale line and that the zero of the main scale is barely visible. What is the thickness of the sheet if the main scale reading is $0.5\; mm$ and the $25^{th}$ division coincides with the main scale line ?

asked Dec 11, 2018 by pady_1

0 answers

Choose the correct statement :

asked Dec 11, 2018 by pady_1

0 answers

If $a,\; b,\; c,\; d$ are inputs to a gate and $x$ is its output, then, as per the following time graph, the gate is :

asked Dec 11, 2018 by pady_1

0 answers

Half-lives of two radioactive elements A and B are 20 minutes and 40 minutes, respectively. Initially, the samples have equal number of nuclei. After 80 minutes, the ratio of decayed numbers of A and B nuclei will be :

asked Dec 11, 2018 by pady_1

0 answers

Radiation of wavelength $\lambda$, is incident on a photocell. The fastest emitted electron has speed $v$. If the wavelength is changed to $\frac{3λ}{4}$ , the speed of the fastest emitted electron will be :

asked Dec 11, 2018 by pady_1

0 answers

The box of a pin hole camera, of length L, has a hole of radius $a$. It is assumed that when the hole is illuminated by a parallel beam of light of wavelength $\lambda$ the spread of the spot (obtained on the opposite wall of the camera) is the sum of its geometrical spread and the spread due to diffraction. The spot would then have its minimum size (say $b_{min}$) when :

asked Dec 11, 2018 by pady_1

0 answers

Ask Questions, Get Answers