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LiF is an example of

A photon of 300 nm is absorbed by a gas, which then re-emits two photons. One re-emitted photon has a wavelength of 400 nm. Calculate the energy of the other photon re-emitted out.

A straight glass tube as shown has 2 inlets $X$ and $Y$ at the two ends of $200\text{cm}$ long tube. $HCl$ gas through inlet $X$ and $N{H}_3$ gas through inlet $Y$ are allowd to enter in the tube at the same time and under the identical conditions. At a point $P$ inside the tube both the gases meet first. The distance of point $P$ from $X$ is:

Arrange the following in increasing order of their $p{K}_a$ value :

Consider the four sulphates: $FeS{O}_4,MnS{O}_4,CoS{O}_4$ and $ZnS{O}_4$. Four separate capsules of these materials have been made containing $0.1$ mole of the substance and are suspended by a thread. A strong magnet is brought close to each capsule. The order of sulphates according to the strength of the response towards the magnet is:

A vessel contains $100$ litres of a liquid X. Heat is supplied to the liquid at a constant pressure of $1$ atm in such a fashion that heat given= change in enthalpy. The volume of the liquid increases by $2$ litres. If $202.6$ joules of heat were supplied, then$[\Delta U,\Delta H=\text{change in internal energy and enthalpy}$ is:

In an adiabatic process, no transfer of heat takes place between system and surroundings. Choose the correct option for free expansion of an ideal gas under adiabatic condition from the following.

Sky looks blue due to [MNR
1986; MP PET 1992]

van der Waals' constants of two gases $X$ and $Y$ are as given:

$\begin{array}{ccc}& a\left(L^{2}atm{\text{mol}}^{-2}\right)& b\left({\text{L mol}}^{-1}\right)\\ \text{Gas}X& 5.6& 0.065\\ \text{Gas}Y& 5.1& 0.012\end{array}$

Which option is true?

The de Brogile wavelength of electron in first Bohr orbit is exactly equal to ?

A reaction : $A_2+B\to$ Products, involves the following mechanism :

$A_2\rightleftharpoons 2A\left(fast\right)$ (A being the intermediate)

$A+B\underset{k_2}{\to }\left(slow\right)$.The rate law consistent to this mechanism is :

The conjugate acid of $N{H}_3$ is :

Equal volumes of oxygen gas and a second gas weigh 1.00 and 2.375 grams respectively under the same experimental conditions. Which of the following is the unknown gas?

Which of the following salts will cause temporary hardness of water?

Which of the following has highest mass

Friedel-Crafts alkylation is expected to proceed through a carbocation intermediate. What would be the alkylation product when benzene reacts with cyclopropyl chloride in the presence of $AlC{l}_3$?

A compound of boron X reacts at ${200}^{\circ }C$ temperature with $N{H}_3$ to give another compound $Y$ which is called as inorganic benzene. The compound $Y$ is a colourless liquid and is highly sensitive. Its melting point is $-{57}^{\circ }C$. The compound $X$ with excess $N{H}_3$ and at a still higher temperature gives boron nitride ${\left(BN\right)}_n$. The compounds $X$ and $Y$ respectively are:

Among group 13 and group 14 elements, which is the most abundant in Earth’s crust?

Which of the following is an energy consuming process?

The ejection of a photoelectron from a metal in the photoelectric effect experiment can by stopped by applying $0.35\text{eV}$ when a radiation of $256.7\text{nm}$ is used. The work function of the metal is:

The α - amino acids, usually exist in the form of zwitter ions. It means they have:

Which of the following graphs represents the Freundlich adsorption isotherm correctly?

Which reaction can't be used for the preparation of the given halogen acid?

Which of the following statements is correct with respect to all amino acids? They are:

The law of mass action was proposed by:

What is the entropy change when 1 mole oxygen gas expands isothermally and reversibly from an initial volume of 10 L to 100 L at 300 K?

Amongst $Ni(CO{)}_4,[Ni(CN{)}_4{]}^{2-}andNiC{l}_4^{2-}:$

H - B - H bond angle in $B{H}_4^{-}$ is:

The compound which contains both ionic and covalent bonds is:

The electrical work done during the reaction at 298 K:

$2H{g}_{\left(l\right)}+C{l}_{2\left(g\right)}\to H{g}_{2}C{l}_{2\left(s\right)},isGiventhat{E}_{\frac{C{l}_2}{C{l}^{-}}}^{\circ }=1.36V;E_{\frac{H{g}_{2}C{l}_2}{Hg,C{l}^{-}}}^{\circ }=0.27V;P_{C{l}_2}=1atm,$

The ratio of $K_p$ to $K_c$ for the equilibrium $CO\left(g\right)+\frac{1}{2}{O}_2\left(g\right)\rightleftharpoons C{O}_2\left(g\right)$ is

The reactivities of methyl chloride, propyl chloride and chlorobenzene are in

the order

[KCET 1988]

The correct order of the decreasing ionic radii among the following isoelectronic species is [CBSE A1PMT 2010]

In the following reaction, how many moles of $KI$ react with 12.5 mol of $K_2{S}_2{O}_8$?

$K_2{S}_2{O}_{8\left(aq\right)}+2K{I}_{\left(aq\right)}\to 2K_{2}S{O}_{4\left(aq\right)}+I_{2\left(s\right)}$

Some statements are given about acylation of amines with acid chloride

I. Tertiary amines do not react with acid chloride

II. This reaction is an example of a nuclophilic addition reaction

III. This reaction is carried out in the presence of pyridine

IV. Aliphatic and aromatic primary and secondary amines involve in this reaction

The correct statements is/ are

Which of the following is not hypovalent but complete its octet?

For the reduction of $N{O}_3^{\ominus }$ ion in an aqueous solution, $E^{\ominus }$ is +0.96 V, the values of $E^{\ominus }$ for some metal ions are given below:

$\left(i\right)V^{2+}\left(aq\right)+2e^{-}\to V;E^{\ominus }=-1.19V$

$\left(ii\right)F{e}^{3+}\left(aq\right)+3e^{-}\to Fe;E^{\ominus }=-0.04V$

$\left(iii\right)A{u}^{3+}\left(aq\right)+3e^{-}\to Au;E^{\ominus }=+1.40V$

$\left(iv\right)H{g}^{2+}\left(aq\right)+2e^{-}\to Hg;E^{\ominus }=+0.86V$



The pair(s) of metals that is/are oxidized by $N{O}_3^{\ominus }$ in aqueous solution is/are

(IIT-JEE, 2010)

Which of the following compounds can undergo nucleophilic substitution easily ?

At high temperature, van der Waal’s equation can be expressed as

Which of the following compounds wil exhibit geometrical isomerism?

Which carbon atom will show minimum electronegativity -

H ${}^{1}C$ $\equiv$ ${}^{2}C$ - C${}^{3}H$ - C${}^{4}H$ - C${}^{5}H$

Which of the following reactions will give a secondary amine as the final nitrogen containing product?

Which of the following reduction reaction does not give an amine as product?

Consider the following redox reaction:



$NaBr{O}_3+6H^{+}+6e^{-}\to NaBr+3H_{2}O$



Calculate the weight of sodium bromate $\left(NaBr{O}_3\right)$ required to prepare $0.6N$ of $100mL$ solution.

(Given : Molar mass of $NaBr{O}_3=151gmo{l}^{-1}$)