Why is H2O a liquid and H2S a gas?
Due to high electronegativity of O than S, H2O undergoes extensive intermolecular H-bonding. As a result, H2O exists as an associated molecule in which each O is tetrahedrally surrounded by four H2O molecules. Therefore, H2O is a liquid at room temperature.
On the other hand,H2S does not undergo H- bonding. It exists as discrete molecules which are held together by weak van der waals forces of attraction. A small amount of energy is required to break these forces of attraction. Therefore, H2S is a gas at room temperature.
Assertion (A): HNO3 makes from passive.
Reason (R): HNO3 forms a protective layer of ferric nitrate on the surface of iron.
Justify the placement of O, S, Se, Te and Po in the same group’of the periodic table in terms of electronic configuration, oxidation state and hydride formation.
In the ring test of NO3 ion.Fe2+ion reduces nitrate ion to nitric oxide, which combines with Fe2+ (aq.) ion to form brown complex. Write the reactions involved in the formation of brown ring.
Assertion (A): HI cannot be prepared by the reaction of KI with concentrated H2SO4.
Reason (R): HI has lowest H – X bond strength among halogen acids.
How is nitrogen prepared in the laboratory? Write the chemical equations of the reactions . involved.
Give the formula and describe the structure of a noble gas species which is isostructural with: (i) ICI4– (ii) IBr2– (iii) Br03–
P4O6 reacts with water according to equation P4O6 + 6H2O Calculate the volume of 0.1 M NaOH solution required to neutralize the acid formed by dissolving 1.1 g of P4O6 in H2O.
Nitric acid forms an oxide of nitrogen on reaction with P4O10. Write the reaction involved. Also write the resonating structures of the oxide of nitrogen formed.
PCl5 reacts with finely divided silver on heating and a white silver salt is obtained, which dissolves on adding excess aqueous NH3 solution. Write the reactions involved to explain what happens.
Match the compounds given in Column I with the hybridization and shape given in Column II and mark the correct option.
Assertion (A): Both rhombic and monoclinic sulphur exist as S8 but oxygen exists as OÏ€.
Reason (R): Oxygen forms pπ-pπ multiple bond due to small size and small bond length but pπ-pπ bonding is not possible in sulphur.
What happens when white phosphorus is heated with concentrated NaOH solution in an inert atmosphere of CO2?
Discuss the general characteristics of Group 15 elements with reference to their electronic configuration, oxidation state, atomic size, ionisation enthalpy and electronegativity.
Why does nitrogen show catenation properties less than phosphorus ? (C.B.S.E. Foreign 2009)
Write balanced equations for the following:
(i) NaCl is heated witlrsulphuric acid in the presence of MnO2
(ii) Chlorine gas is passed into a solution of Nal in water.
With which neutral molecule is ClO– isoelectronic? Is this molecule Lewis acid or base ? (Pb. Board 2009)
