Multiple Choice QuestionsFor the four successive transition elements (Cr, Mn, Fe and Co), the stability of +2 oxidation state will be there in which of the following order?
(At. no. Cr = 24, Mn = 25, Fe = 26, Co = 27)
Fe > Mn > Co> Cr
Co > Mn > Fe > Cr
Cr > Mn > Co > Fe
Cr > Mn > Co > Fe
Acidified K2Cr2O7 solution turns green when Na2SO3 is added to it. This is due to the formation of
CrO42-
Cr2(SO3)3
CrSO4
CrSO4
Gadolinium belongs to 4f series. Its atomic number is 64. which of the following is the correct electronic configuration of gadolinium?
[Xe]4f8 6d2
[Xe]4f95s1
[Xe]4f7 5d16s2
[Xe]4f7 5d16s2
Assuming complete ionisation, same moles of which of the following compounds will require the least amount of acidified KMnO4 for complete oxidation?
FeSO4
FeSO3
FeC2O4
FeC2O4
Which of the statements given below is incorrect?
Cl2O7 is an anhydride of perchloric acid
O3molecule is bent
ONF is isoelectronic with NO2
ONF is isoelectronic with NO2
Which one of the following compounds is a peroxide?
KO2
BaO2
MnO2
MnO2
B.
BaO2
In peroxides, the oxidation state of O is -1 and they give H2O2, with dilute acids, and have peroxide linkage.
In KO2,
+1 + (x X 2) = 0
x = -1/2 (thus, it is a superoxide, not a peroxide.)
In BaO2, + 2 + (x X 2) = 0
x = -1
Thus, it is a peroxide. Only it gives H2O2 when reacts with dilute acids and has peroxide linkage as
Ba2+ [ O- O]2-
Peroxide linkage
In MnO2 and NO2, Mn and N exhibit variable oxidation states, thus, the oxidation state of O in these is -2. Hence, these are not peroxides. Thus, it is clear that among the given molecules only BaO2 is a peroxide.
Which of the following ions will exhibit colour in aqueous solutions?
La3+ (Z = 57)
Ti3+ (Z = 22)
Lu3+
Lu3+
Which of the following oxidation states is the most common among the lanthanoids
4
2
5
5
The Number of moles of KMnO4 that will be needed to react with one mole of sulphite ion in acidic solution is:
3/5
4/5
2/5
1
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