The s-Block Elements Test 32

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The s-Block Elements Test 32

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Weekly Quiz Competition

Question 1
1 / -0

For the alkali metals, which of the following increases atomic number ?

A
First ionization energy

B
Electronegativity

C
Hydration energy of the univalent ion

D
Atomic radius

Solution

when atomic no is increase so atomic size is increase and atomic radius is also increase
Question 2
1 / -0

Which of the following compounds is formed when sodium burns in excess supply of air ?

A
Sodium suboxide

B
Sodium oxide

C
Sodium peroxide

D
Sodium superoxide

Solution

when sodium burns in excess supply of air Sodium peroxide is produces
Question 3
1 / -0

Match List-I with List-II and select the correct answer using the codes given below the lists:
(A) $$BaSO_{4} + ZnS$$ (1) Explosive
(B) $$NI_{3}$$ (2) Oxidiser in rocket propellants
(C) $$N_{2}O_{4}$$ (3) Space capsule
(D) $$KO_{2}$$ (4) Pigment

A
$$A - 3, B - 1, C - 4, D - 2$$

B
$$A - 4, B - 1, C - 2, D - 3$$

C
$$A - 3, B - 4, C - 1, D - 2$$

D
$$A - 4, B - 3, C - 2, D - 1$$

Solution

$$BaSO_4 + ZnS$$ this show pigment type of reaction
$$NI_3$$ show the explosive type of reaction
$$N_2O_4$$ show oxidiser in rocket propellsnts
$$KO_2$$ is show in Space capsule

hence B is correct answer
Question 4
1 / -0

Mg and Li are similar in their properties due to

A
Same e/m ratio

B
same electron afinity

C
same group

D
same ionic potential

Solution

$$ Li $$ and $$ Mg $$ ions have similar polarising power or ionic potential.
Hence, Option "D" is the correct answer.
Question 5
1 / -0

The solubility in water of sulphates down the Be group is $$ be > Mg > Ca >Sr > Ba $$ This is due to

A
Increase in melting point

B
High ionization energy

C
Higher coordination number

D
All of those

Solution

As the size increases, the extent of hydration i.e. coordination number decreases and hence the solubility decreases accordingly.
Hence, Option "C" is the correct answer.
Question 6
1 / -0

Which of the following statement is incorrect?

A
Across a period, the trend of radius and ionisation energy are generally opposite to each other.

B
The metallic radius of potassium is greater than its covalent radius.

C
Amongst $$Li^{-},\:Be^{-},\:B^{-}$$ and $$C^{-},\: Li^{-}$$ is least stable ion.

D
Atomic and ionic radii of niobium and tantalum are almost same.

Solution

(A) Across the period, size decreases as electrons are added in the same shell and nuclear charge increases by one unit for addition of each successive element. On the contrary, the ionization energy increases as size of atom decreases and nuclear charge increases.
(B) $$r_{metallic} > r_{covalent}$$ as covalent bond formation involves the overlapping of orbitals. In potassium, $$r_{metallic} = 235\ pm$$ while, $$r_{covalent} = 203\ pm$$.
(C) $$Li^- : 1s^2 2s^2$$; completely filled stable configuration, so more stable.
$$Be^-: 1s^2 2s^2 2p^1$$
$$B^- : 1s^2 2s^2 2p^2$$
$$C^- : 1s^2 2s^2 2p^3$$; half filled stable configuration
(D) Due to lanthanide contraction.
Question 7
1 / -0

Which of the following will have the largest size in water?

A
$$Rb^{+}$$

B
$$Na^{+}$$

C
$$K^{+}$$

D
$$Li^{+}$$

Solution

Among the given ions, $$Li^+$$ ion has the maximum charge density due to its small ionic size. Hence, it undergoes hydration to maximum extent. Thus, the size of hydrated $$Li^+$$ ion is the maximum among the given ions.
Small size has high hydration energy.
Question 8
1 / -0

The solubility of II group hydroxides increases with molecular weight. This is because:

A
lattice energy is same but hydration energy decreases down the group.

B
hydration energy is same but lattice energy decreases down the group.

C
both lattice and hydration energy increase down the group.

D
decrease in lattice energy down the group is faster than decrease in hydration energy.

Solution

On moving down the group II, the atomic and ionic size increases. The size of $$Be^{2+}$$ is smallest and the size of $$Ba^{2+}$$ is highest. As the size increases, the decrease in the lattice energy is much more than the decrease in the hydration energy. Due to this, the solubility increases with increase in the molecular weight on moving down the group.

Hence, barium hydroxide is more soluble than beryllium hydroxide.
Question 9
1 / -0

A substance which gives brick red colour in flame test and breaks down on heating to give oxygen and a brown gas is :

A
magnesium nitrate

B
calcium nitrate

C
barium nitrate

D
strontium nitrate

Solution

Calcium nitrate gives brick red colour in flame test and breaks down on heating to give oxygen and a brown gas ($$NO_2$$).
Question 10
1 / -0

Arrange the following elements in the increasing order of their atomic radii:

A
$$Na < Li < Rb < C < K$$

B
$$Cs < Rb < K < Na < Li$$

C
$$K < Rb < Cs < Na < Li$$

D
$$Li < Na < K < Rb < Cs$$

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The s-Block Elements Test 32

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The s-Block Elements Test 32

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SHARING IS CARING

Question 1

First ionization energy

Electronegativity

Hydration energy of the univalent ion

Atomic radius

Solution

Question 2

Sodium suboxide

Sodium oxide

Sodium peroxide

Sodium superoxide

Solution

Question 3

$$A - 3, B - 1, C - 4, D - 2$$

$$A - 4, B - 1, C - 2, D - 3$$

$$A - 3, B - 4, C - 1, D - 2$$

$$A - 4, B - 3, C - 2, D - 1$$

Solution

Question 4

Same e/m ratio

same electron afinity

same group

same ionic potential

Solution

Question 5

Increase in melting point

High ionization energy

Higher coordination number

All of those

Solution

Question 6

Across a period, the trend of radius and ionisation energy are generally opposite to each other.

The metallic radius of potassium is greater than its covalent radius.

Amongst $$Li^{-},\:Be^{-},\:B^{-}$$ and $$C^{-},\: Li^{-}$$ is least stable ion.

Atomic and ionic radii of niobium and tantalum are almost same.

Solution

Question 7

$$Rb^{+}$$

$$Na^{+}$$

$$K^{+}$$

$$Li^{+}$$

Solution

Question 8

lattice energy is same but hydration energy decreases down the group.

hydration energy is same but lattice energy decreases down the group.

both lattice and hydration energy increase down the group.

decrease in lattice energy down the group is faster than decrease in hydration energy.

Solution

Question 9

magnesium nitrate

calcium nitrate

barium nitrate

strontium nitrate

Solution

Question 10

$$Na < Li < Rb < C < K$$

$$Cs < Rb < K < Na < Li$$

$$K < Rb < Cs < Na < Li$$

$$Li < Na < K < Rb < Cs$$

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