Recent questions in JEEMAIN PAST PAPERS

For 1 molal aqueous solution of the following compounds, which one will show the highest freezing point ?

asked Dec 11, 2018 by pady_1

1 answer

Which of the following compounds contain(s) no covalent bond(s) ? $KCl, \; PH_3,\; O_2, \; B_2H_6, \;H_2SO_4$

asked Dec 11, 2018 by pady_1

0 answers

Which of the following are Lewis acids?

asked Dec 11, 2018 by pady_1

0 answers

The combustion of benzene $(l)$ gives $CO_2(g)$ and $H_2O (l)$. Given that heat of combustion of benzene at constant volume is $-3263.9 \; kJ\; mol^{-1}$ at $25^{\circ}C$; heat of combustion (in $kJ\; mol^{-1}$) of benzene at constant pressure will be - $(R = 8.314 \;JK^{-1} mol^{-1})$

asked Dec 11, 2018 by pady_1

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Which type of 'defect' has the presence of cations in the interstitial sites ?

asked Dec 11, 2018 by pady_1

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The oxidation states of $Cr$ in $[Cr(H_2O)_6]Cl_3, [Cr(C_6H_6)_2]$, and $K_2[Cr(CN)_2(O)_2(O_2)(NH_3)]$ respectively are :

asked Dec 11, 2018 by pady_1

0 answers

The predominant form of histamine present in human blood is ($pK_a$ , Histidine = 6.0)

asked Dec 11, 2018 by pady_1

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The compound that does not produce nitrogen gas by the thermal decomposition is :

asked Dec 11, 2018 by pady_1

0 answers

The recommended concentration of fluoride ion in drinking water is up to 1 ppm as fluoride ion is required to made teeth enamel harder by converting $ [3Ca_3(PO_4)_2.Ca(OH)_2]$ to:

asked Dec 11, 2018 by pady_1

0 answers

An aqueous solution contains $0.10\; M \;H_2S$ and $0.20\; M \; HCl$. If the equilibrium constant for the formation of $HS^-$ from $H_2S$ is $1.0 \times 10^{-7}$ and that of $S^{2-}$ from $HS^-$ ions is $1.2 \times 10^{-13}$ then the concentration of $S^{2-}$ ions in aqueous solution is :

asked Dec 11, 2018 by pady_1

0 answers

When metal 'M' is treated with NaOH, a white gelatinous precipitate 'X' is obtained, which is soluble in excess of NaOH. Compound 'X' when heated strongly gives an oxide which is used in chromatography as an adsorbent. The metal M is :

asked Dec 11, 2018 by pady_1

0 answers

Which of the following compounds will be suitable for Kjeldahl's method for nitrogen estimation ?

asked Dec 11, 2018 by pady_1

0 answers

An aqueous solution contains an unknown concentration of $Ba^{2+}$. When $50\; mL$ of the $1M$ solution of $Na_2SO_4$ is added, $BaSO_4$ just begins to precipitate. The final volume is $500\; mL$. The solubility product of $BaSO_4$ is $1 \times 10^{-10}$. What is the original concentration of $Ba^{2+}$.

asked Dec 11, 2018 by pady_1

0 answers

Phenol on treatment with $CO_2$ in the presence of $NaOH$ followed by acidification produces a compound $X$ as the major product. $X$ on treatment with $(CH_3 CO_2)O$ in presence of catalytic amount of $H_2SO_4$ produced :

asked Dec 11, 2018 by pady_1

0 answers

The major product of the following reaction is :

asked Dec 11, 2018 by pady_1

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Consider the following reaction and statements : $[Co(NH_3)_4Br_2]^+ + Br^- \to [Co(NH_3)_3Br_3] + NH_3$ (i) Two isomers are produced if the reactant complex ion is a cis-isomer. (ii) Two isomers are produced if the reactant complex ions is a trans-isomer. (iii) Only one isomer is produced if the reactant complex ion is a trans-isomer. (iv) Only one isomer is produced if the reactant complex ion is a cis-isomer. The correct statements are :

asked Dec 11, 2018 by pady_1

0 answers

Glucose on prolonged heating with $HI$ gives :

asked Dec 11, 2018 by pady_1

0 answers

At $518^{\circ}C$, the rate of decomposition of a sample of gaseous acetaldehyde, initially at a pressure of $363 $ Torr, was $1.00 \; Torr\;s^{-1}$ when $5\%$ had reacted and $0.5\; Torr\; s^{-1}$ when $33\%$ had reacted. The order of the reaction is :

asked Dec 11, 2018 by pady_1

0 answers

Which of the following lines correctly show the temperature dependence of equilibrium constant $K$, for an exothermic reaction ?

asked Dec 11, 2018 by pady_1

0 answers

How long (approximate) should water be electrolysed by passing through 100 amperes current so that the oxygen released can completely burn 27.66 g of diborane ? (Atomic weight of B = 10.8 u)

asked Dec 11, 2018 by pady_1

0 answers

The major product formed in the following reaction is :

asked Dec 11, 2018 by pady_1

0 answers

Hydrogen peroxide oxidises $[Fe(CN)_6]^{4-}$ to $[Fe(CN)_6]^{3-}$ in acidic medium but reduces $[Fe(CN)_6]^{3-}$ to $[Fe(CN)_6]^{4-}$ in alkaline medium. The other products formed are, respectively.

asked Dec 11, 2018 by pady_1

0 answers

The ratio of mass percent of $C$ and $H$ of an organic compound $(C_XH_YO_Z)$ is $6:1$. If one molecule of the above compound $(C_XH_YO_Z)$ contains half as much oxygen as required to burn one molecule of compound $C_XH_Y$ completely to $CO_2$ and $H_2O$. The empirical formula of compound $C_XH_YO_Z$ is :

asked Dec 11, 2018 by pady_1

0 answers

The trans-alkenes are formed by the reduction of alkynes with ?

asked Dec 11, 2018 by pady_1

1 answer

An alkali is titrated against an acid with methyl orange as indictor, which of the following is a correct combination ?

asked Dec 11, 2018 by pady_1

0 answers

The increasing order of basicity of the following compounds is :

asked Dec 11, 2018 by pady_1

0 answers

Phenol reacts with methyl chloroformate in the presence at $NaOH$ to form product A. A reacts with $Br_4$ to form product B. A and B respectively

asked Dec 11, 2018 by pady_1

0 answers

Which of the following salts is the most basic in aqueous solution ?

asked Dec 11, 2018 by pady_1

0 answers

The total number of lone pair of electrons in $I^-_3$ ion is :

asked Dec 11, 2018 by pady_1

0 answers

Let the orthocenter and centroid of a triangle be A (-3, 5) and B (3, 3) respectively. If C is the circumcentre of this triangle, then the radius of the circle having line segement AC as diameter, is :

asked Dec 11, 2018 by pady_1

1 answer

Let A be the sum of the first 20 terms and B be sum of the first 40 terms of the series $1^2 + 2.2^2 + 3^2 + 2.4^2 + 5^2+2.6^2 + ...$ If $B - 2A = 100 \lambda$, then $\lambda$ is equal to :

asked Dec 11, 2018 by pady_1

1 answer

From 6 different novels and 3 different dictionaries, 4 novels and 1 dictionary are to be selected and arranged in a row on a shelf so that the dictionary is always in the middle. The number of such arrangements is :

asked Dec 11, 2018 by pady_1

1 answer

PQR is a triangular park with PQ = PR = 200 m. A. T. V. tower stands at the mid-point of QR. If the angles of elevation of the top of the tower at P, Q and R are respectively $45^{\circ},\; 30^{\circ}$ and $30^{\circ}$, then the height of the tower (in m) is :

asked Dec 11, 2018 by pady_1

2 answers

The length of the projection of the line segment joining the points $(5, -1, 4)$ and $(4, -1, 3)$ on the plane, $x+y+z=7$ is

asked Dec 11, 2018 by pady_1

1 answer

Let $\overrightarrow{u}$ be a vector coplanar with the vectors $\overrightarrow{a} = 2 \hat{i} + 3 \hat{j} - \hat{k} $ and $\overrightarrow{b} = \hat{j} + \hat{k}$. If $\overrightarrow{u}$ is perpendicular to and $\overrightarrow{a}$ and $\overrightarrow{u} \overrightarrow{b} = 24$, then $| \overrightarrow{u}|^2$ is equal to :

asked Dec 11, 2018 by pady_1

1 answer

Let $y = y(x)$ be the solution of the differential equation $\sin x \frac{dy}{dx} + y \cos x = 4 x, \; x \subset (0, \pi)$. If $y (\frac{\pi}{2})=0$, then $y (\frac{\pi}{6})$ is equal to

asked Dec 11, 2018 by pady_1

1 answer

Let $S = \{ t \in R : f(x) = |x-\pi|. (e^{|x|} - 1) \sin |x|$ is not differentiable at $t\}$. Then the set $S$ is equal to :

asked Dec 11, 2018 by pady_1

1 answer

The integral $\begin{align} \int \frac{\sin^2 x \cos^2 x}{(\sin^5 x + \cos^3 x \sin^2 x + \sin^3 x \cos^2x + \cos^5x)^2} \end{align} \; dx$ is equal to: (where C is a constant of integration)

asked Dec 11, 2018 by pady_1

1 answer

If $\displaystyle\sum_{i=1}^{9} (x_i - 5) = 9$ and $ \displaystyle\sum_{i=1}^{9} (x_i - 5)^2 = 45$ then the standard deviation of the 9 items $x_1, \; x_2, .... x_9$ is :

asked Dec 11, 2018 by pady_1

1 answer

For each $t \in R$ let $[t]$ be the greatest integer less than or equal to $t$. Then $ \displaystyle\lim_{x \to 0^-} x$ $\begin{pmatrix} [\frac{1}{x} +[\frac{2}{x}] +....+[\frac{15}{x}] \end{pmatrix}$

asked Dec 11, 2018 by pady_1

1 answer

Let $g(x) = \cos x^2, \; f(x) = \sqrt{x}$ and $\alpha, \;\beta \;(\alpha < \beta)$ be the roots of the quadratic equation $18x^2-9 \pi x + x^2 = 0$. Then the area (in sq. units) bounded by the curve $y=(gof)(x) $ and the lines $x = \alpha,\; x = \beta$ and $y =0$, is

asked Dec 11, 2018 by pady_1

1 answer

The value of $\begin{align} \int_{-\frac{\pi}{2}}^{\frac{\pi}{2}} \frac{\sin^2 x}{1+2^x} dx \end{align}$ is :

asked Dec 11, 2018 by pady_1

1 answer

A straight line through a fixed point $(2, 3)$ intersects the coordinate axes at distinct points P and Q. If O is the origin and the rectangle OPRQ is completed, then the locus of R is

asked Dec 11, 2018 by pady_1

1 answer

Let $a_1, a_2, a_3,.....,a_{49}$ be in A.P. such that $\displaystyle\sum_{k=0}^{12} a_{4k+1}=416$ and $a_9 + a_{43} =66$. If $a_1^2 + a_2^2....a_{17}^2=140\;m$ then $m$ is equal to :

asked Dec 11, 2018 by pady_1

1 answer

The sum of the co-effiicients of all odd degree terms in the expansion of $(x + \sqrt{x^3-1})^5 + (x-\sqrt{x^3 - 1})^5, (x>1)$ is :

asked Dec 11, 2018 by pady_1

1 answer

If $\begin{vmatrix} x-4 & 2x & 2x \\ 2x & x-4 & 2x \\ 2x & 2x & x-4 \end{vmatrix}= (A + Bx)(x-A)^2$ then the ordered pair (A, B) is equal to :

asked Dec 11, 2018 by pady_1

1 answer

Tangent and normal are drawn at $P(16, 16)$ on the parabola $y^2 =16x$, which intersect the axis of the parabola at A and B, respectively. If $C$ is the centre of the circle through the points $P, \;A$ and $B$ and $\angle CPB=\theta$, then a value of $\tan \theta$ is :

asked Dec 11, 2018 by pady_1

1 answer

The Boolean expression $\sim (p \lor q) \lor (\sim p \land q)$ is equivalent to :

asked Dec 11, 2018 by pady_1

1 answer

Two sets A and B are as under : $A =\{ (a,b) \in R \times R : |a-5|<1$ and $|b-5| <1\} $; $B= \{(a,b) \in R \times R$: $4(a-6)^2 + 9(b-5)^2 \leq 36 \}$. Then ;

asked Dec 11, 2018 by pady_1

1 answer

Let $f(x) = x^2 + \frac{1}{x^2} $ and $g(x) = x - \frac{1}{x},\; x \in R -\{-1, 0, 1\}$. If $h(x) = \frac{f(x)}{g(x)}$, then the local minimum value of $h(x)$ is :

asked Dec 11, 2018 by pady_1

1 answer

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