The s-Block Elements Test 33

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The s-Block Elements Test 33

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Weekly Quiz Competition

Question 1
1 / -0

The fuel in the atomic pile is:

A
thorium

B
sodium

C
petroleum

D
uranium
Question 2
1 / -0

The hydration energy of $$Mg^{2+}$$ is larger than that of

A
$$Al^{3+}$$

B
$$Na^+$$

C
$$Be^{2+}$$

D
$$Mg^{3+}$$

Solution

Hydration energy depends on ionic radii and radii decreases as we move along column from left to right and increases down the group, also as positive charge increases, radii dereases. As radii increases, hydration energy decreases. So among all given options only sodium ion has bigger radii than $$Mg^{+2}$$ so it has lower hydration energy than $$Mg^{+2}$$. Hydration energy of $$Na^{+} = -435$$ KJ/mol. Hydration energy of $$Mg^{+2} = -1921$$ KJ/mol.
Question 3
1 / -0

Which of the following forms the most basic hydroxide?

A
$$Cu$$

B
$$Al$$

C
$$Na$$

D
$$Zn$$

Solution

As sodium has highest oxidation potential among all. So it has highest tendency for oxidation reaction and it forms most basic hydroxide.

Question 4

1 / -0

A chemistry student trying to detect the metallic ion in a salt makes a paste on the clean $$Pt$$ wire-loop of the salt with concentrated $$HCl.$$ When he takes a small amount of this paste and keeps it in a non-luminous Bunsen flame, the color of the flame changes to grassy green. He should, therefore, conclude that the metal is:

$$Mg$$

$$Ca$$

$$Ba$$

$$Ra$$

Solution

A chemistry student trying to detect the metallic ion in a salt makes a paste on the clean $$Pt$$ wire-loop of the salt with concentrated $$HCl$$. When he takes a small amount of this paste and keeps it in a non-luminous Bunsen flame, the color of the flame changes to grassy green. He should , therefore, conclude that the metal is Barium $$(Ba)$$. The table below gives a rough color guide for the elements.

	Flame color :
$$Li =$$	red
$$Na =$$	strong, persistent orange
$$K =$$	lilac (pink)
$$Rb =$$	red (red-violet)
$$Cs =$$	blue/violet (see below)
$$Ca =$$	orange-red
$$Sr =$$	red
$$Ba =$$	pale green
$$Cu =$$	blue-green (often with white flashes)
$$Pb =$$	gray-white

Question 5
1 / -0

The metallic luster exhibited by sodium is explained by :

A
diffusion of sodium ions

B
oscillations of loose electrons

C
excitation of free protons

D
existence of body centered cubic lattice

Solution

Sodium: It is shiny and many of the properties of metal can be related to something called "metallic bonding". An over simplified description of metallic bonding is the "electron-sea model" in which a metal is envisioned as an array of metal cations surrounded by a sea of mobile electrons.
The metallic luster of metals - their shininess, and reflectivity - is due to the absorption and emission of light without changing the wavelength of the photon. Light is absorbed by the electrons, but rather than the energy being converted to heat or to emission of a different wavelength, the energy is emitted at the same wavelength.
Question 6
1 / -0

Nitrolim is a :

A
mixture of calcium carbide and nitrogen

B
mixture of calcium cyanamide and carbon

C
mixture of calcium cyanide and carbon

D
mixture of $$NH_4 CN$$ and $$CaCN$$

Solution

When nitrogen is passed over calcium carbide at a suitable high temperature, we get a mixture called nitrolim which is a nitrogenous fertilizer, which is a mixture of calcium cyanamide and carbon.
Question 7
1 / -0

Which of the following metal sulphide is water soluble?

A
$$CaS$$

B
$$ZnS$$

C
$$HgS$$

D
$$CdS$$

Solution

Calcium sulphide, $$CaS$$ and zinc sulphide $$ZnS$$ are slightly soluble in water.
Cadmium sulphide $$CdS$$ and mercury (II) sulfide are insoluble in water.
Question 8
1 / -0

X and Y are two metals. When burnt in air, X forms only oxide while Y forms oxide and nitride. The metals X and Y may be :

A
$$Ca$$ and $$Mg$$

B
$$Na$$ and $$Mg$$

C
$$Li$$ and $$Na$$

D
$$Na$$ and $$K$$

Solution

Reaction with air;
$$Mg+air\rightarrow MgO+Mg_3N_2$$
and,
sodium forms peroxide and monoxide as product with air
$$Na+air\rightarrow Na_2O_2+Na_2O$$.
Question 9
1 / -0

Which of the following statement is incorrect?

A
Sodium and potassium are soft and silvery white metals.

B
Sodium and potassium in air get tarnished due to the formation of a layer of oxide or carbonates.

C
Sodium and potassium burn in dry oxygen (excess) gives peroxides.

D
Sodium and potassium are kept under kerosene to avoid contact with air and moisture.

Solution

(A) Sodium and potassium are soft and silvery-white metals. The softness is due to the presence of a single electron in the valence shell in a large-sized metal which produces a weak metallic bonds.
Thus, option A is correct.

(B) Sodium and potassium in the air get tarnished due to the formation of a layer of oxide or carbonates. Hence, they are stored in kerosene or paraffin oil.
Thus, option B is correct.

(C) Sodium burns in dry oxygen (excess) to form peroxide. Potassium burns in dry oxygen (excess) to form superoxide.
Thus, option C is incorrect.

(D) Sodium and potassium are soft and silvery-white metals. The softness is due to the presence of a single electron in the valence shell in a large-sized metal which produces a weak metallic bonds.
Thus, option D is correct.

The only incorrect option is C. Hence, option C is the answer.
Question 10
1 / -0

Which of the following reagent is used as fixer in photography?

A
$$AgBr$$

B
$$AgNO_{3}$$

C
$$Na_{2}S_{2}O_{3}\cdot 5H_{2}O$$

D
Both A and C

Solution

$$Na_{2}S_{2}O_{3}$$ (as fixer) dissolves unreacted $$AgBr$$ as:
$$2Na_{2}S_{2}O_{3} +AgBr\rightarrow Na_{3}[Ag(S_{2}O_{3})_{2}] + NaBr $$

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The s-Block Elements Test 33

Result

The s-Block Elements Test 33

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SHARING IS CARING

Question 1

thorium

sodium

petroleum

uranium

Question 2

$$Al^{3+}$$

$$Na^+$$

$$Be^{2+}$$

$$Mg^{3+}$$

Solution

Question 3

$$Cu$$

$$Al$$

$$Na$$

$$Zn$$

Solution

Question 4

$$Mg$$

$$Ca$$

$$Ba$$

$$Ra$$

Solution

Question 5

diffusion of sodium ions

oscillations of loose electrons

excitation of free protons

existence of body centered cubic lattice

Solution

Question 6

mixture of calcium carbide and nitrogen

mixture of calcium cyanamide and carbon

mixture of calcium cyanide and carbon

mixture of $$NH_4 CN$$ and $$CaCN$$

Solution

Question 7

$$CaS$$

$$ZnS$$

$$HgS$$

$$CdS$$

Solution

Question 8

$$Ca$$ and $$Mg$$

$$Na$$ and $$Mg$$

$$Li$$ and $$Na$$

$$Na$$ and $$K$$

Solution

Question 9

Sodium and potassium are soft and silvery white metals.

Sodium and potassium in air get tarnished due to the formation of a layer of oxide or carbonates.

Sodium and potassium burn in dry oxygen (excess) gives peroxides.

Sodium and potassium are kept under kerosene to avoid contact with air and moisture.

Solution

Question 10

$$AgBr$$

$$AgNO_{3}$$

$$Na_{2}S_{2}O_{3}\cdot 5H_{2}O$$

Both A and C

Solution

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