List of top Chemistry Questions

X and Y in reactions:

X and Y in reaction sequence:

IUPAC names of benzene derivatives are respectively:

Increase in concentration of 'X' in blood of pregnant women who smoke may induce premature delivery. What is 'X'?

Correct statements regarding halides of group 14 elements:
I. Stability of dihalides: SiX$_2$ > GeX$_2$ > SnX$_2$ > PbX$_2$
II. SnF$_4$, PbF$_4$ are ionic
III. PbI$_4$ does not exist

The reaction/s which represent the production of diborane on an industrial scale is/are:
I. 4BF$_3$ + 3LiAlH$_4$ → 2B$_2$H$_6$ + 3LiF + 3AlF$_3$
II. 2NaBH$_4$ + I$_2$ → B$_2$H$_6$ + 2NaI + H$_2$
III. 2BF$_3$ + 6NaH → B$_2$H$_6$ + 6NaF

Among alkaline earth metals, metal with least melting point is:

Identify correctly matched sets:
I. NaHCO$_3$ - fire extinguisher
II. Na$_2$CO$_3$ - water softening
III. NaOH - purification of bauxite

Which of the following is used as stabilizer for H$_2$O$_2$?

Given $K_p$ for $2AO_2 + O_2 \rightleftharpoons 2AO_3$ is $4 \times 10^{10}$. Find $K_p'$ for $3AO_3 \rightleftharpoons 3AO_2 + \frac{3}{2} O_2$.

Identify the correct statements:
I. Energy of an isolated system is constant
II. In a closed system, exchange of both energy and matter is possible
III. Enthalpy is extensive

At 27$^\circ$C, 100 mL of 0.05 M Cu$^{2+}$ solution is added to 1 L of 0.1 M KI. Find [KI] in resultant solution.

Isotherms ($p$-$V$ lines) of one mole of an ideal gas at $T_1$ and $T_2$ have slope ratio 1:2. If $T_1=1000$ K, find $T_2$.

Identify the pairs in which both molecules do not possess same type of hybridization:
I. H$_2$O, SO$_2$
II. PCl$_3$, NH$_3$
III. SO$_2$, SO$_3$
IV. BCl$_3$, NCl$_3$

Which of the following statements are correct?
I. The increasing order of covalent character of NaCl, RbCl, MgCl$_2$ is RbCl < NaCl <\ MgCl$_2$
II. The high boiling point of water is due to intramolecular hydrogen bonding
III. H$_2$O has more dipole moment among NH$_3$, H$_2$O, and HF

Ionization enthalpies of the elements X, Y, Z having successive atomic numbers respectively are 2080, 496, 737 kJ mol$^{-1}$. X, Y, Z are:

Among Li, Na, O, S, the elements having the most negative electron gain enthalpy and least negative electron gain enthalpy respectively are:

Observe the elements from H (Z=1) to Ca (Z=20). How many elements have no unpaired electrons in their ground state?

According to Bohr's theory of hydrogen atom, the approximate angular momentum of electron in H atom in the ground state is ($h = 6.62 \times 10^{-34}$ Js):

Applying the Hückel rule, the number of aromatic compounds among the following is _ _ _. (in integer)

The standard enthalpy of formation of methane (\(CH_4\)), using the standard enthalpy of reaction values from the following reaction steps, is \(-x\) kcal/mol. The value of \(x\) is _ _ _. (round off to one decimal place)

If a weak acid \(HA\) is \(0.1\%\) ionized (dissociated) in a \(0.2M\) solution, its pH will be _ _ _. (round off to one decimal place)

The number of distinct products formed after the nitration of tetralone in the presence of \(HNO_3\) and \(H_2SO_4\) is _ _ _. (in integer)