The d- and f- Block Elements Test

Result

The d- and f- Block Elements Test - 43

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Weekly Quiz Competition

Question 1
1 / -0

Which of the following is diamagnatie?

A
$$Cr^{3+}$$

B
$$V^{2+}$$

C
$$Sc^{3+}$$

D
none

Solution
Question 2
1 / -0

Magnetic moment $$2.83\ BM$$ is given by which of the following ions?
(At. nos. $$Ti=22,Cr=24,Mn=25,Ni=28$$)

A
$${Ti}^{3+}$$

B
$${Ni}^{2+}$$

C
$${Cr}^{3+}$$

D
$${Mn}^{2+}$$

Solution
Question 3
1 / -0

Which of the following becomes paramagnetic on heating?

A
$$MnO$$

B
$$Fe_3O_4$$

C
$$ZnFe_2O_4$$

D
$$B$$ and $$C$$ both

Solution

Ferrimagnetic change their nature on heating and become paramagnetic
eg. $$Fe_3O_4, ZnFe_2O_4, MgFe_2O_4$$
Question 4
1 / -0

Magnetic moment of $${}_{{\text{25}}}{\text{M}}{{\text{n}}^{{\text{x + }}}}{\text{ is }}\sqrt {{\text{15}}} $$ B.M then the value of x is :

A
1

B
2

C
3

D
4

Solution
Question 5
1 / -0

Which one of the following ion(s) is/are paramagnetic?

A
$$Al^{3+}$$

B
$$Fe^{2+}$$

C
$$K^+$$

D
$$Mg^{2+}$$

Solution
Question 6
1 / -0

The magnetic moment for $${ Ti }^{ 2+ }$$, $${ V }^{ 3+ }$$ and $${ Ni }^{ 2+ }$$ is ________ .

A
4.90

B
3.87

C
2.83

D
1.73

Solution
Question 7
1 / -0

$$Gd\ (64)$$ has _________ unpaired electrons with sum of spin __________.

A
$$7, 3.5$$

B
$$8, 3$$

C
$$6, 3$$

D
$$8, 4$$

E
$$9, 3.5$$

Solution

The element $$Gd(Z=64)$$ show electronic configuration$$=[Xe]_{54}\cdot 4f^7, 5d^1, 6s^2$$.

As it has $$8$$ - unpaired electrons ($$4f^7$$ and $$5d^1$$) and its sum of spin $$=8\times \dfrac{1}{2}=4$$.
Question 8
1 / -0

Uranium is a radioactive element but it is also a typical metal. What is not a property of uranium?

A
It can be hammered into shape

B
It conducts heat

C
It is used as a source of energy

D
It forms covalent compounds

Solution

$$\text{Uranium is a radioactive element which decay continuously. So it cannot form a covalent compound.}$$
Question 9
1 / -0

In $$Sc^{3+},Ti^{2+},Ti^{3+},V^{2+}$$, increasing order of spin only magnetic moment is:

A
$$Sc^{3+} < Ti^{2+} < Ti^{3+}< V^{2+}$$

B
$$Sc^{3+} < Ti^{3+} < Ti^{2+}< V^{2+}$$

C
$$Ti^{2+} < Sc^{3+} < Ti^{3+}< V^{2+}$$

D
$$Sc^{3+} < Ti^{2+} < V^{2+}< Ti^{3+}$$

Solution

Solution:- (B) $${Sc}^{3+} < {Ti}^{+3} < {Ti}^{+2} < {V}^{2+}$$
$$\mu=\sqrt{n(n+2)}$$ B.M
For magnetic moment to be higher, number of unpaired electron must be higher
$$Sc^{3+}\Rightarrow 3d^0$$ $$\mu=0$$
$$Ti^{2+}\Rightarrow 3d^2$$ $$\sqrt8$$ B.M
$$Ti^{3+}\Rightarrow 3d^1$$ $$\sqrt3$$ B.M
$$V^{2+}\Rightarrow 3d^3$$ $$\sqrt{15}$$ B.M
Question 10
1 / -0

The ionic charges on chromate ion and dichromate ion respectively is:

A
$$-2, -2$$

B
$$-3, -2$$

C
$$-2, -4$$

D
$$-4, -2$$

Solution

Chromate salts contain the chromate anion, $$CrO_4^{2−}$$ with -2 ionic charge.

Dichromate salts contain the dichromate anion, $$Cr_2O_7^{2-}$$ with -2 ionic charge.

They are oxoanions of chromium in the +6 oxidation state.

Hence, option $$A$$ is correct.