Home
Class 12
CHEMISTRY
(i)with reference to structural variabil...

(i)with reference to structural variability and chemical reactivity write the differences between lanthanoids and actinoids
(ii) Mame a member of the lanthanoid series which is well known to exhibit +4 oxidation state
(iii) Complete the following equation :`MnO_(4)^(-)+8H^(+)+5e^(-)rarr`
(iv) out of `Mn^(3+)` and `Cr^(3+)` which is ore paramagnetic and why? Atomic nos : Mn =25 Cr =24

Text Solution

Verified by Experts

(i) Lanthanoids/Acitinoids
(a) They are not radioactive (expect pm ) but they are radioactive
(b) They mainly show `+3` oxidation state. .They can show up to '+7' oxidation state
(c ) Their magnetic nature can be easily explained .But their magnetic nature can not be easily explained .
(d) Their physical and chemical properities have been studied throughly . but their physical and chemical properties have not been studied throughly
(ii) cerium (Ce)
(iii) `MnO_4-+8H+5e-Mn_2++42H_2O`
(iv)`Mn^(+3)=[Ar]` 4 so `3d^(4)(4"unparied") e^(-)Cr^(+3)=[Ar]4 S_(3)d_(3) "unpaired" e^(-))"Mn"^(+3) "has more no of unpaired" e^(-) "has" Cr^(+3) " Hence " Mn^(3+)` is more paramagnetic .
Doubtnut Promotions Banner Mobile Dark
|

Topper's Solved these Questions

  • XII BOARDS

    XII BOARDS PREVIOUS YEAR|Exercise Outside Delhi : SET-II|13 Videos

  • XII BOARDS

    XII BOARDS PREVIOUS YEAR|Exercise Outside Delhi : SET-III|14 Videos

  • XII BOARDS

    XII BOARDS PREVIOUS YEAR|Exercise C.B.S.E. CLASS - XII|30 Videos

  • SAMPLE PAPER 2019

    XII BOARDS PREVIOUS YEAR|Exercise SECTION: D|1 Videos

Similar Questions

Explore conceptually related problems

(i) Name the element of 3d transition series which shows maximum number of oxidation states. Why does it show so ? (ii)Which transition metal of 3d series ha positive E^(@)(M^(2+)//M) value and why ? (iii) Out of Cr^(3+) and Mn^(3+) , which is a stronger oxidizing agent and why ? (iv) Name a member of the lanthanoid series which is well known to exhibit + 2 oxidation state. (v) Complete the following equation : MnO_(4)^(-) + 8H^(+) + 5e^(-) to .

(i) Name the element of 3d transition series which shows maximum number of oxidation states. Why does it show so? (ii) Which transition metal of 3d series has positive E^(@)(M^(2+)//M) value and why? (iii) Out of Cr^(3+) and Mn^(3+) , which is a stronger oxidising agent and why? (iv) Name a member of the lanthanoid series which is well known to exhibit +2 oxidation state. (v) Complete the following equation : MnO_(4)^(-)+8H^(+)+5e^(-)to

Name the reducing agent in the following reaction : 3MnO_(2) + 4 Al rarr 3Mn + 2 Al_(2) O_(3) State which is more reactive, Mn or Al and why ?

(a) How do you prepare : (i) K_(2)MnO_(4) from MnO_(2) (ii) Na_(2)Cr_(2)O_(7) from Na_(2)CrO_(4) ? (b) Account for the following : (i) Mn^(2+) is more stable than Fe^(2+) towards oxidation to +3 state. (ii) The enthalpy of atomisation is lowest for Zn in 3d series of transition elements. (iii) Actinoid elements show wide range of oxidation states. or (i) Name the elements of 3d transition series which shows maximum number of oxidation states. Why dows it show so ? (ii)Which transition element of 3d series has positive E_(M^(+)//M)^(@) value and why ? (iii) Out of Cr^(3+) and Mn^(3+) which is stronger oxidizing agent and why ? (iv) Name a member of the lanthanoid series which is well known to exhibit +2 oxidation state. (v) Complete the equation : MnO_(4)^(-) +8 H^(+) + 5e^(-) rarr

Name the following: (a) A transition metal which does not exhibit variation in oxidation state in its compounds. (b) A compound where the transition metal is the +7 oxidation state. (c) A member of the lanthanoid series which is well known to exhibit +4 oxidation state. (d) Ore used in the preparation of Potassium dichromate.

Complete the following chemical equations : (i) 8MnO_(4)^(-)+3S_(2)O_(3)^(2-)+H_(2)O to (ii) Cr_(2)O_(7)^(2-)+3Sn^(2+)+14H^(+) to

(a) Give three points of difference between lanthanoids and actinoids. (b) Give reason and select on one atom/ion which will exhibit asked property: (i) Sc^(3+) or Cr^(3+) (exhibit diamagnetic behaviour) (ii) Cr or Cu (high melting and boiling point)

(i) Which transition element in 3d series has positive E_(M^(2+//)M)^(@) value and why ? (ii) Name a member of lanthanoid series which is well known to exhibit to exhibit +4 oxidation state and why? (b) Account for the following : (i) The highest oxidation state is exhibited in oxoanions of transition metals. (ii) HCl is not used to acidify KMnO_(4) solution. (iii) Transition metals have high enthalpy of atomisation.

(a) Complete the following chemical reaction equation : (i)MnO_(4(aq))^(-)+C_(2)O_(4(aq))^(2-)+H_(aq)^(+) to (ii) Cr_(2)O_(7(aq))^(2-)+Fe_((aq))+H_((aq))^+to (b) Explain the following observation about the transition /inner transition elements: (i) There is in general an increase in density of element from titanium (Z=22) to copper (Z=29) (ii) there occurs much more frequent metal bonding in compounds of heavy transition elements (3^(rd) series) (iii) The members of the actinoid series exhibit a larger number of oxidation states than the corresponding members of the lanthanoid series (a) Complete the following chemical equation for reaction: (i) 8MnO_(4)^(-)+H_(2)O+3S_(2)O_(3)^(2-) to (ii) Cr_(2)O_(7)^(2-)+3H_(2)S+8H^(+) to (b) Give an explanation for each of the following observations: (i) The gradual decrease in size (actinoid contractions) from element to element is greater among the actinoids than among the lanthanoids (lanthanoid contraction). (ii) The greatest number of oxidation states are exhibited by the members in the middle of a transition series. (iii) With the same d-orbital configuration (d^(4) Cr^(2+)) ion is a reducing agent but Mn^(3+) ion is an oxidising agent.

(a) Account for the following: (i) Ce^(4+) is a strong oxidising agent in aqueous solution. (ii) Transition metals have high enthalpy of atomisation. (iii) Mn shows maximum number of oxidation states in 3d series. (b) Complete the following equations: (i) 2MnO_(4)^(-)+6H^(+)+5NO_(2)^(-)to (ii) Cr_(2)O_(7)^(2-)+14H^(+)+6Fe^(2+)to

Home
Profile