List of top Chemistry Questions

In graphite, the C-C bond length within the layer is X pm and the distance between two adjacent layers is Y pm. X and Y respectively are:
Match the elements in List-1 with their characteristic flame colors in List-2: [h] {|l|l|} List -1 (Element) & List -2 (Flame Color)
(A) Na & (I) Apple green
(B) Ca & (II) yellow
(C) Ba & (III) Brick red
(D) Li & (IV) Crimson red
Match the water softening methods in List-1 with the chemicals/reagents in List-2: [h] {|l|l|} List -1 (Method) & List -2 (Reagent)
(A) Calgon method & (I) RSO\(_3\)H
(B) Ion exchange method & (II) Ca(OH)\(_2\)
(C) Clark's method & (III) NaAlSiO\(_4\)
(D) Synthetic resin method & (IV) Na\(_6\)(PO\(_3\))\(_6\)
The solubility of \(Mg_3(PO_4)_2\) is \(S\) mol L\(^{-1}\). The solubility product is given by the relation:
Which one of the pairs will form a buffer solution?
The conjugate acid of $NH_2^-$ is:
Consider the equilibrium reactions:

\(H_3PO_4 \rightleftharpoons H^+ + H_2PO_4^-\) \((K_1)\)
\(H_2PO_4^- \rightleftharpoons H^+ + HPO_4^{2-}\) \((K_2)\)
\(HPO_4^{2-} \rightleftharpoons H^+ + PO_4^{3-}\) \((K_3)\)

The equilibrium constant, \(K_c\), for the following dissociation:

\(H_3PO_4 \rightleftharpoons 3H^+ + PO_4^{3-}\)

is:
The number of extensive and intensive properties in the list given below is respectively:
Density, enthalpy, mass, temperature, volume, pressure
The signs of $\Delta$H and $\Delta$s for a reaction to be spontaneous at all temperatures respectively are
For which of the following process entropy change ($\Delta$S) is negative ?
• [I)] Sublimation of dry ice
• [II)] Freezing of water
• [III)] Crystallisation of the dissolved substance
• [IV)] Burning of rocket fuel
For the reaction N$_2$ + 3H$_2$ $\rightarrow$ 2NH$_3$, $\Delta$H = ?
At 273 K the maximum work done when pressure on 10g of hydrogen is reduced from 10atm to 1 atm under isothermal, reversible conditions is
An organic compound has the empirical formula CH$_2$O. Its vapour density is 45. The molecular formula of compound is
Which of the following pairs of gases contains the same number of molecules?
Calculate the amount of \( CO_2 \) gas produced, when \( 32 \)g of \( CH_4 \) is burned with sufficient amount of oxygen (Given atomic weight of \( C=12, O=16 \) and \( H=1 \))
Identify the correct set of molecules with zero dipole moment.
The IUPAC name of an element with atomic number \( 119 \) is:
Identify the correct set of molecules with zero dipole moment:
The energy of the second bohr orbit of the hydrogen atom is $-328 \text{ kJ mol}^{-1}$; hence the energy of the fourth bohr orbit would be:
Which of the following sets are correctly matched? {|c|c|c|} Set & Molecule & Geometry
I & $\text{BrF}_5$ & Square pyramidal
II & $\text{XeF}_6$ & Distorted octahedral
III & $\text{SF}_4$ & Square planar
IV & $\text{PbCl}_2$ & Linear
Consider the equilibrium reactions:
The equilibrium constant, $K_c$, for the overall dissociation \[ H_3PO_4 \rightleftharpoons 3H^+ + PO_4^{3-} \] is:
Identify the correct set of molecules with zero dipole moment:
Which of the following orders is not correct for the given property?
The IUPAC name of an element with atomic number 119 is:
The energy of the second bohr orbit of the hydrogen atom is $-328 \, \text{kJ mol}^{-1}$; hence the energy of the fourth bohr orbit would be: