Recent questions tagged the-p-block-elements

Description : Which aerosol deplete ozone layer ?

Last Answer : Ans C.F.C  

Description : Write the formula of tear gas . 

Last Answer : Ans : CCl3 NO2 

Description : Why is helium used in diving apparatus ?

Last Answer : Ans: Because heliun is very low solubility in blood  

Description : Why H3 PO3 is dibasic and H3PO4 is tribasic ?

Last Answer : Ans In H3PO3 only two replacable hydrogen but inH3PO4 , three hydrogens are replacable .  

Description : Are all the five bonds in PCl5 molecule equivalent ? 

Last Answer : Ans – PCl5 has a trigonal bipyramidal structure and the three equatorial p-cl bonds are equivalent . while trhe two axial bonds are different and longer than equatorial bonds. 

Description : How is the presence of SO2 detected ?

Last Answer : Ans : 1. It has pungent characteristic smell . 2. It decolourises KMn O4 solution 3. It turns acidified K2 Cr2 O7 green 

Description : Why is fluorine stronger Oxidising agent ?

Last Answer : Ans: Due to (a) Low enthalpy of dissociation (b) high enthalpy of Hydration of F-

Description : Halogens have maximum negative electron gain enthalpy in the respective periods in the P. T Why ? 

Last Answer : Ans Due to smallest size and high effective nuclear charge , readily accept one electron  to acquire noble gas electronic configuration  

Description : Which forms of Sulphur show paramagnetic behaviour ?

Last Answer : Ans : In Vapour State sulphurPartly exists as S2 molecule which has two unpaired electrons in the * Orbitals hence exhibit paramagnetic 

Description : Give reasons i) H2O is a liquid but H2S a gas. ii) Ammonia has higher boiling point than phosphine ii) Krypton & xenon make compounds.

Last Answer : Ans: i) Hydrogen bond is found in H2O but not in H2S.  ii) Hydrogen bond is found in NH3 but not in PH3.  iii) Because they have low ionization energy.

Description : Find hybridization and shape i) XeF2 ii) XeO3 iii) XeF4

Last Answer : Ans: i) sp3d, Linear ii) sp3, Pyramidal iii) sp3d2 , Square planar

Description : How is ammonia prepared? Write chemical reaction involved in the Haber’s process.

Last Answer : i) Ammonia is prepared by the combination of hydrogen and nitrogen in the ratio of 3:1.  ii) The used catalyst is iron oxide. The promotors are potassium and aluminium oxides.  iii) The required conditions are high pressure and moderate temperature.  N2 + 3H2 → 2NH3

Description : Nitrogen shows anomalous behaviour in the group. Why?

Last Answer : Ans: i) Small size ii) High electro negativity iii) Absence of vacant d-orbital.

Description : Give reasons: a) Phosphorous pentachloride is unstable. b) Phosphorous trichloride fumes in moisture.

Last Answer : Ans: a) Because of two longer axial bonds. b) Because it reacts with water and forms hydrochloric acid. 

Description : Ortho phosphoric acid is triprotic but phosphoric acid is diprotic. Why?

Last Answer : Ans: Because of their structures ortho phosphoric acid and phosphoric acid have three and two ionisable hydrogen.

Description : Write shape of following molecules: a) Ammonia b) Phosphorous Pentachloride

Last Answer : Ans: a) Pyramidal b) Trigonal bipyramidal

Description : Ammonia is water soluble. Why?

Last Answer : Ans: It forms hydrogen bond with water. 

Description : Why is Nitrogen relatively inert?

Last Answer : Ans: Because of a triple bond with high bond energy. 

Description : Why Nitrogen is a gas whereas Phosphorous is a solid?

Last Answer : Ans: Nitrogen molecules have less Vander Waal’s forces of attraction whereas molecular phosphorous has more Vander Waal’s forces of attraction.

Description : Why is Ammonia a good complexing agent?

Last Answer : Ans: Because of lone pair of electrons on N. 

Description : Why is phosphine weaker base than Ammonia?

Last Answer : Ans: P is bigger than N, therefore lone pair of electrons are less available on P than N.