D And F Block Elements(11th And 12th > Chemistry ) Questions and answers for exam Preparation

11th And 12th > Chemistry

D AND F BLOCK ELEMENTS MCQs

Total Questions : 45 | Page 1 of 5 pages

Question 1.

The correct order of ionic radii for $Y^{3 +}, E u^{3 +}, L a^{3 +}, L u^{3 +}$

$L a^{3 +} < E u^{3 +} < L u^{3 +} < Y^{3 +}$
$Y^{3 +} < L u^{3 +} < E u^{3 +} < L a^{3 +}$
$L u^{3 +} < Y^{3 +} < E u^{3 +} < L a^{3 +}$
$L u^{3 +} < E u^{3 +} < L a^{3 +} < Y^{3 +}$

Discuss Question

Answer: Option B. ->

Y^{3 +} < L u^{3 +} < E u^{3 +} < L a^{3 +}

:
B

Y belongs to $5^{t h}$ period & La belongs to $6^{t h}$ period. Ionic radii increases from $Y^{3 +} t o L a^{3 +}$ down the group. Due to lanthanoid contraction, ionic radii follows the order
$L u^{3 +} < E u^{3 +} < L a^{3 +}$

Question 2.

Which ion has maximum magnetic moment?

$V^{+ 3}$
$M n^{+ 3}$
$F e^{+ 3}$
$C u^{+ 2}$

Discuss Question

Answer: Option C. ->

F e^{+ 3}

:
C

\begin{matrix} S . N o . & O u t e r c o n f i g u - r a t i o n & N o . o f u n p a i r e d e^{-} & C o l o u r o f i o n & M a g n e t i c m o m e n t V^{+ 3} & 3 d^{2} & 2 & G r e e n & 2.76 M n^{+ 3} & 3 d^{4} & 4 & V i o l e t & 1.9 F e^{+ 3} & 3 d^{5} & 5 & Y e l l o w & 5.96 C u^{+ 2} & 3 d^{9} & 1 & B l u e & 1.9 \end{matrix}

Question 3.

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

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

Discuss Question

Answer: Option A. -> The +4 oxidation state of cerium is not known in solutions
:
A
(+4) oxidation state of cerium is also known in solution. The formation of Ce(+4) is favoured by its noble gas configuration, but it is a strong oxidant reverting to the common +3 state.

Question 4.

The lanthanide contraction is responsible for the fact that

Zr and Y have about the same radius
Zr and Nb have similar oxidation state
Zr and Hf have about the same radius
Zr and Zn have the same oxidation sate

Discuss Question

Answer: Option C. -> Zr and Hf have about the same radius
:
C
Atomic radii down the group for transition elements first increases, becomes almost equal and then decreases. This is due to poor shielding of one of 4f electron by another in the subshell which results in greater effective nuclear charge; this effect is called lanthanide contraction.

Question 5.

The aqueous solution containing which one of the following ions will be colourless

$S c^{+ 3}$
$F e^{+ 2}$
$T i^{+ 3}$
$M n^{+ 2}$

Discuss Question

Answer: Option A. ->

S c^{+ 3}

:
A

S c^{+ 3} ⟶ 1 s^{2} 2 s^{2} 2 p^{6} 3 s^{2} 3 p^{6}

Due to presence of paired electron it will be colourless.

Question 6.

One of the following metals forms a volatile carbonyl compound and this property is taken advantage of for its extraction. This metal is

Iron
Nickel
Cobalt
Tungsten

Discuss Question

Answer: Option B. -> Nickel
:
B
Nickel; Ni + 4CO

⟶

[N i (C O)_{4}]

(volatile)

Question 7.

Of the following outer electronic configurations of atoms, the highest oxidation state is achieved by which one of them

$(n - 1) d^{3} n s^{2}$
$(n - 1) d^{5} n s^{1}$
$(n - 1) d^{8} n s^{2}$
$(n - 1) d^{5} n s^{2}$

Discuss Question

Answer: Option D. ->

(n - 1) d^{5} n s^{2}

:
D

$(n - 1) d^{5} n s^{2}$ can achieve the maximum oxidation state of +7.

Question 8.

Read the assertion and reason carefully to mark the correct option out of the options given below:
(a)If both assertion and reason are true and the reason is the correct explanation of the assertion.
(b)If both assertion and reason are true but reason is not the correct explanation of the assertion.
(c)If assertion is true but reason is false.
(d) If assertion is false but reason is true.
Assertion : $N a_{2} C r_{2} O_{7}$ is not a primary standard solution in volumetric analysis.
Reason : $N a_{2} C r_{2} O_{7}$ is hygroscopic.

Discuss Question

Answer: Option A. -> a
:
A
- Hygroscopic substances have affinity for water. Since sodium salt has a greater solubility in water and is extensively used as an oxidising agent in organic chemistry, whereas, Potassium dichromate is used as a primary standard in volumetric analysis.

Question 9.

Which of the following transition metal is present in misch metal?

Discuss Question

Answer: Option A. -> La
:
A
Misch metal is an alloy of rare earth metals with composition :
Rare earth metals – 94.95%
Iron (Fe) – 5%
S,C,Ca,Cl... – Traces
A good deal of mischmetal is used in Mg-based alloy to produce bullets, shell and lighter flint.

Question 10.

Read the assertion and reason carefully to mark the correct option out of the options given below:
(a)If both assertion and reason are true and the reason is the correct explanation of the assertion.
(b)If both assertion and reason are true but reason is not the correct explanation of the assertion.
(c)If assertion is true but reason is false.
(d)If assertion is false but reason is true.
Assertion : EV(M $^{2 +}$ /M) value for copper is positive (+0.34V).
Reason : High ionization enthalpy and low heat of hydration energy

Discuss Question

Answer: Option A. -> a
:
A
Second ionization enthalpy for copper is higher than other elements of 3-d series which is not compensated by low heat of hydration.