Q. Concentrated nitric acid, upon long standing, turns yellow-brown due to the formation of :

1. $N_2{O}_4$
2. $NO$
3. $N{O}_2$
4. $N_{2}O$

Q. Sulfide ores are common for the metals:

1. Ag, Cu and Sn
2. Ag, Mg and Pb
3. Al, Cu and Pb
4. Ag, Cu and Pb

Q. The standard enthalpies of formation of $C{O}_2\left(g\right)$, $H_{2}O\left(l\right)$ and glucose(s) at ${25}^{o}C$ are $-400kJmo{l}^{-1},-300kJmo{l}^{-1}$ and $-1300KJmo{l}^{-1}$, respectively. The standard enthalpy of combustion per gram of glucose at ${25}^{o}C$ is:

1. $+2900kJ$
2. $-2900kJ$
3. $-16.11kJ$
4. $+16.11kJ$

Q. Consider the following complex ions, $P,Q$ and $R$,

1. $R<Q<P$
2. $Q<R<P$
3. $R<P<Q$
4. $Q<P<R$

Q. Upon treatment with ammoniacal $H_{2}S$, the metal ion that precipitates as a sulfide is:

1. $Fe\left(III\right)$
2. $Zn\left(II\right)$
3. $Mg\left(II\right)$
4. $Al\left(III\right)$

Q. Methylene blue is adsorbed on activated charcoal at ${25}^{0}C$ from its aqueous solution. Which is the correct statement for this process?

1. The adsorption requires activation at ${25}^{0}C$.
2. The adsorption is accompanied by a decrease in enthalpy.
3. The adsorption increases with increase of temperature.
4. The adsorption is irreversible.

Q. $KI$ in acetone, undergoes ${S_N}^2$ reaction with each of $P,Q,R$ and $S$. The rates of the reaction vary as _______________.

1. $Q>R>P>S$
2. $P>Q>R>S$
3. $S>P>R>Q$
4. $R>P>S>Q$

Q. In the reaction, $P+Q\to R+S$, the time taken for 75% reaction of P is twice the time taken for 50% reaction of P. The concentration of Q varies with reaction time as shown in the figure. The overall order of the reaction is:

1. 2
2. 3
3. 0
4. 1

Q. The compound that does not liberate $C{O}_2$, on treatment with aqueous sodium bicarbonate solution, is:

1. benzoic acid
2. salicylic acid
3. carbolic acid (phenol)
4. benzenesulphonic acid

Q. The initial rate of hydrolysis methyl acetate ($1M$) by a weak acid ($HA,1M$) is $1/{100}^{th}$ of that of a strong acid ($HX,1M$), at ${25}^{o}C$. The $K_a$of $HA$ is:

1. 1 x 10${}^{-4}$
2. 1 x 10${}^{-6}$
3. 1 x 10${}^{-5}$
4. 1 x 10${}^{-3}$

Q. The arrangement of $X^{-}$ions around $A^{+}$ ion in solid $AX$ is given in the figure (not drawn to scale). If the radius of $X^{-}$ is $250$ pm, the radius (in pm) of $A^{+}$ will be:

1. $104$
2. $125$
3. $183$
4. $57$