d- and f-Block Elements · JEE Main previous year questions

The sum of the total number of bonds between chromium and oxygen atoms in chromate and dichromate ions is ____________.

Ferrous sulphate heptahydrate is used to fortify foods with iron. The amount (in grams) of the salt required to achieve 10 ppm of iron in 100 kg of wheat is _______. Atomic weight : Fe = 55.85; S = 32.00; O = 16.00

The purest from of commercial iron is :

1. A.pig iron
2. B.wrought iron
3. C.cast iron
4. D.scrap iron and pig iron

Consider the hydrated ions of $\mathrm{T}{\mathrm{i}}^{2+}$, ${\mathrm{V}}^{2+}$, $\mathrm{T}{\mathrm{i}}^{3+}$, and $\mathrm{S}{\mathrm{c}}^{3+}$. The correct order of their spin-only magnetic moments is :

1. A.$\mathrm{S}{\mathrm{c}}^{3+}<\mathrm{T}{\mathrm{i}}^{3+}<{\mathrm{V}}^{2+}<\mathrm{T}{\mathrm{i}}^{2+}$
2. B.$\mathrm{S}{\mathrm{c}}^{3+}<\mathrm{T}{\mathrm{i}}^{3+}<\mathrm{T}{\mathrm{i}}^{2+}<{\mathrm{V}}^{2+}$
3. C.$\mathrm{T}{\mathrm{i}}^{3+}<\mathrm{T}{\mathrm{i}}^{2+}<\mathrm{S}{\mathrm{c}}^{3+}<{\mathrm{V}}^{2+}$
4. D.${\mathrm{V}}^{2+}<\mathrm{T}{\mathrm{i}}^{2+}<\mathrm{T}{\mathrm{i}}^{3+}<\mathrm{S}{\mathrm{c}}^{3+}$

The number of water molecule(s) not coordinated to copper ion directly in $\mathrm{CuS}{\mathrm{O}}_4.5{\mathrm{H}}_2\mathrm{O}$, is :

1. A.2
2. B.4
3. C.3
4. D.1

The maximum prescribed concentration of copper in drinking water is :

1. A.3 ppm
2. B.5 ppm
3. C.0.5 ppm
4. D.0.05 ppm

The pair of metal ions that can give a spin only magnetic moment of 3.9 BM for the complex $[\mathrm{M}({\mathrm{H}}_2\mathrm{O}{)}_6]C{l}_2$, is -

1. A.${\mathrm{V}}^{2+}$ and $\mathrm{F}{\mathrm{e}}^{2+}$
2. B.${\mathrm{V}}^{2+}$ and $\mathrm{C}{\mathrm{o}}^{2+}$
3. C.$\mathrm{C}{\mathrm{o}}^{2+}$ and $\mathrm{F}{\mathrm{e}}^{2+}$
4. D.$\mathrm{C}{\mathrm{r}}^{2+}$ and $\mathrm{M}{\mathrm{n}}^{2+}$

The highest value of the calculated spin only magnetic moment (in BM) among all the transition metal complexes is :

1. A.5.92
2. B.6.93
3. C.3.87
4. D.4.90

1. A.
2. B.
3. C.
4. D.

The pair having the same magnetic moment is : [At. No.: $\mathrm{Cr}=24,\mathrm{Mn}=25,\mathrm{Fe}=26,\mathrm{Co}=27$]

1. A.$[\mathrm{Cr}({\mathrm{H}}_2\mathrm{O}{)}_6{]}^{2+}$ and $[\mathrm{Fe}({\mathrm{H}}_2\mathrm{O}{)}_6{]}^{2+}$
2. B.$[\mathrm{Mn}({\mathrm{H}}_2\mathrm{O}{)}_6{]}^{2+}$ and $[\mathrm{Cr}({\mathrm{H}}_2\mathrm{O}{)}_6{]}^{2+}$
3. C.$[\mathrm{CoC}{\mathrm{l}}_4{]}^{2-}$ and $[\mathrm{Fe}({\mathrm{H}}_2\mathrm{O}{)}_6{]}^{2+}$
4. D.$[\mathrm{Cr}({\mathrm{H}}_2\mathrm{O}{)}_6{]}^{2+}$ and $[\mathrm{CoC}{\mathrm{l}}_4{]}^{2-}$

The concentration of fluoride, lead, nitrate and iron in a water sample from an underground lake was found to be 1000 ppb, 40 ppb, 100 ppm and 0.2 ppm, respectively. This water is unsuitable for drinking due to high concentration of :

1. A.Lead
2. B.Nitrate
3. C.Iron
4. D.Fluoride

Which series of reactions correctly represents chemical relations related to iron and its compound?

1. A.$\mathrm{Fe}\stackrel{dil.{\mathrm{H}}_2\mathrm{S}{\mathrm{O}}_4}{\to }\mathrm{FeS}{\mathrm{O}}_4\stackrel{{\mathrm{H}}_2\mathrm{S}{\mathrm{O}}_4,{\mathrm{O}}_2}{\to }\mathrm{F}{\mathrm{e}}_2(\mathrm{S}{\mathrm{O}}_4{)}_3\stackrel{heat}{\to }\mathrm{Fe}$
2. B.$\mathrm{Fe}\stackrel{{\mathrm{O}}_2,heat}{\to }\mathrm{FeO}\stackrel{dil.{\mathrm{H}}_2\mathrm{S}{\mathrm{O}}_4}{\to }\mathrm{FeS}{\mathrm{O}}_4\stackrel{heat}{\to }\mathrm{Fe}$
3. C.$\mathrm{Fe}\stackrel{\mathrm{C}{\mathrm{l}}_2,heat}{\to }\mathrm{FeC}{\mathrm{l}}_3\stackrel{heat,air}{\to }\mathrm{FeC}{\mathrm{l}}_2\stackrel{\mathrm{Zn}}{\to }\mathrm{Fe}$
4. D.$\mathrm{Fe}\stackrel{{\mathrm{O}}_2,heat}{\to }\mathrm{F}{\mathrm{e}}_3{\mathrm{O}}_4\stackrel{\mathrm{CO},600^{\circ }\mathrm{C}}{\to }\mathrm{FeO}\stackrel{\mathrm{CO},700^{\circ }\mathrm{C}}{\to }\mathrm{Fe}$

Magnetic moment of $\mathrm{G}{\mathrm{d}}^{3+}$ ion ($Z=64$) is

1. A.$3.62\mathrm{BM}$
2. B.$9.72\mathrm{BM}$
3. C.$7.9\mathrm{BM}$
4. D.$10.60\mathrm{BM}$

In context with the transition elements, which of the following statements is incorrect ?

1. A.In addition to the normal oxidation states, the zero oxidation state is also shown by these elements in complexes.
2. B.In the highest oxidation states, the transition metal show basic character and form cationic complexes.
3. C.In the highest oxidation states of the first five transition elements (Sc to Mn), all the 4s and 3d electrons are used for bonding
4. D.Once the ${\mathrm{d}}^5$ configuration is exceeded, the tendency to involve all the 3d electrons in bonding decreases.

Lanthanoid contraction is caused due to :

1. A.the appreciable shielding on outer electrons by 4f electrons from the nuclear charge
2. B.the appreciable shielding on outer electrons by 5d electrons from the nuclear charge
3. C.the same effective nuclear charge from Ce to Lu
4. D.the imperfect shielding on outer electrons by 4f electrons from the nuclear charge

The lanthanide contraction is responsible for the fact that :

1. A.Zr and Y have about the same radius
2. B.Zr and Nb have similar oxidation state
3. C.Zr and Hf have about the same radius
4. D.Zr and Zn have the same oxidation

Which of the following factors may be regarded as the main cause of lanthanide contraction?

1. A.Poor shielding of one of 4f electron by another in the subshell
2. B.Effective shielding of one of 4f electrons by another in the subshell
3. C.Poorer shielding of 5d electrons by 4f electrons
4. D.Greater shielding of 5d electrons by 4f electrons

The value of the 'spin only' magnetic moment for one of the following configurations is $2.84\mathrm{BM}$. The correct one is :

1. A.$d^4$ (in strong ligand field)
2. B.$d^4$ (in weak ligand field)
3. C.$d^3$ (in weak as well as in strong fields)
4. D.$d^5$ (in strong ligand field)

Alkyl halides react with dialkyl copper reagents to give

1. A.alkenes
2. B.alkyl copper halides
3. C.alkanes
4. D.alkenyl halides

The oxidation state of chromium in the final product formed the reaction between $KI$ and acidified potassium dichromate solution is :

1. A.$+3$
2. B.$+2$
3. C.$+6$
4. D.$+4$

Cerium (Z = 58) is an important member of the lanthanoids. Which of the following statements about cerium is incorrect?

1. A.The common oxidation states of cerium are +3 and +4
2. B.Cerium (IV) acts as an oxidizing agent
3. C.The +4 oxidation state of cerium is not known in solutions
4. D.The +3 oxidation state of cerium is more stable than the +4 oxidation state

The correct order of magnetic moments (spin only values in B.M.) among is : (Atomic numbers: Mn = 25; Fe = 26, Co =27)

1. A.$[\mathrm{MnC}{\mathrm{l}}_4{]}^{2-}>[\mathrm{CoC}{\mathrm{l}}_4{]}^{-2}>[\mathrm{Fe}(\mathrm{CN}{)}_6{]}^{-4}$
2. B.$[\mathrm{Fe}(\mathrm{CN}{)}_6{]}^{-4}>[\mathrm{CoC}{\mathrm{l}}_4{]}^{2-}>[\mathrm{MnC}{\mathrm{l}}_4{]}^{2-}$
3. C.$[\mathrm{Fe}(\mathrm{CN}{)}_6{]}^{4-}>[\mathrm{MnC}{\mathrm{l}}_4{]}^{2-}>[\mathrm{CoC}{\mathrm{l}}_4{]}^{2-}$
4. D.$[\mathrm{MnC}{\mathrm{l}}_4{]}^{2-}>[\mathrm{Fe}(\mathrm{CN}{)}_6{]}^{4-}>[\mathrm{CoC}{\mathrm{l}}_4{]}^{2-}$

Which one of the following is reduced with zinc and hydrochloric acid to give the corresponding hydrocarbon?

1. A.Ethyl acetate
2. B.Butan-2-one
3. C.Acetamide
4. D.Acetic acid

Which of the following ions has the maximum magnetic moment?

1. A.$\mathrm{M}{\mathrm{n}}^{2+}$
2. B.$\mathrm{F}{\mathrm{e}}^{2+}$
3. C.$\mathrm{T}{\mathrm{i}}^{2+}$
4. D.$\mathrm{C}{\mathrm{r}}^{2+}$

The type isomerism present in nitropentammine chromium (III) chloride is :

1. A.optical
2. B.linkage
3. C.ionization
4. D.polymerisation.