List of top Questions asked in JEE Main- 2013

Number of atoms in the following samples of substances is largest in :

For gaseous state, if most probable speed is denoted by $c *$, average speed by $\overline{C}$ and root square speed by $c$, then for a large number of molecules, the ratios of these speeds are

Experimentally it was found that a metal oxide has formula $ M_{0.98}O. $ Metal $M$, present as $ M^{2+} $ and $ M^{3+} $ in its oxide.Fraction of the metal which exists as $ M^{3+} $ would be

Which of the following is diamagnetic?

Copper crystallises in fcc with a unit length of $361\,pm$. What is the radius of copper atom ?

Which of the following arrangements does not represent the correct order of the property stated against it?

Calcination is the process in which:

Electron gain enthalpy with negative sign of fluorine is less than that of chlorine due to :

A solution of $(-) 1-chloro-1-$phenylethane in toluene racemises slowly in the presence of a small amount of $SbCl_5$, due to the formation of

A compound with molecular mass $180$ is acylated with $CH_3COCl$ to get a compound with molecular mass $390$. The number of amino groups present per molecule of the former compound is

A gaseous hydrocarbon gives upon combustion $0.72\, g$ of water and $3.08\, g$ of $CO_2$. The empirical formula of the hydrocarbon is

A major component of Borsch reagent is obtained by reacting hydrazine hydrate with which of the following ?

Glycosidic linkage is actually an :

Consider the following reaction, $xMnO_4^- + yC_2O_4^{2-}+zH^+ \rightarrow xMn^{2+}+2yCO_2 + \frac{z}{2}H_2O$ The values of x, y and z in the reaction are, respectively

Which of the following represents the correct order of increasing first ionisation enthalpy for $Ca, Ba, S, Se$ and $Ar$?

Vapour pressure of pure benzene is $119$ torr and that of toluene is $37.0$ torr at the same temperature. Mole fraction of toluene in vapour phase which is in equilibrium with a solution of benzene and toluene having a mole fraction of toluene $0.50$, will be :

Formaldehyde can be distinguished from acetaldehyde by the use of :

$10\, mL$ of $2(M)$ $NaOH$ solution is added to $200\, mL$ of $0.5 (M)$ of $NaOH$ solution. What is the final concentration ?

How many grams of methyl alcohol should be added to $10$ litre tank of water to prevent its freezing at $268\, K$ ? $\left(K_{f} \, for\, water\, is \,1.86 K\, kg \, mol^{-1} \right)$

Which one has the highest boiling point?

Which one of the following is most stable?

The rate constant of a zero order reaction is $2.0 \times 10^{-2}\, mol \,L^{-1}\, s^{-1}$. If the concentration of the reactant after $25$ seconds is $0.5\,M$. What is the initial concentration ?

Compound $( A ), C_8H_9Br$ gives a white precipitate when warmed with alcoholic $AgNO_3$. Oxidation of $(A)$ gives an acid $(B)$, $C_8H_6O$ 4. $(B)$ easily forms anhydride on heating. Identify the compound $(A)$.

The order of reactivity of the given haloalkanes towards nucleophile is :

Oxidation state of sulphur in anions $SO^{2-}_{3}. S_{2}O^{2-}_{4}$ and $S_{2}O^{2-}_{6}$ increases in the orders: