Chemistry Test 207

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Chemistry Test 207

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Weekly Quiz Competition

Question 1
4 / -1

Which of the following can replace zinc from ZnSO₄ solution?

A
Copper

B
Mercury

C
Iron

D
Aluminium
Solution
Aluminium is more electropositive than zinc. Hence, aluminium can replace zinc from its salt solution.

2Al(s) + 3ZnSO₄(aq) → Al₂(SO₄)₃+3Zn(s)

Zinc has the ability to displace iron and copper from their respective salt solutions and therefore is more reactive than them.

Fe(s) + ZnSO₄(aq) → no reaction

Cu(s) +ZnSO₄(aq) → no reaction

Reactivity of elements is in the following order :
- Aluminium is more reactive than zinc.
- Zinc is more reactive than iron and copper.
Question 2
4 / -1

Which of the following compounds will not undergo decomposition on passing electricity through the aqueous solution?

A
Sugar

B
Sodium acetate

C
Sodium chloride

D
Sodium bromide

Solution

Sodium acetate, sodium chloride and sodium bromide are the electrolytes, i.e., they produce respective ions in their aqueous solution. On the other hand, sugar is a non-electrolyte, i.e., does not produce ions in aqueous solution. Thus, no electrolysis occurs on the passing of electricity through aqueous sugar solution.
Question 3
4 / -1

Most of the times to determine the temperature in an electric furnace, thermometer containing thermocouple is used. From the e.m.f. of the thermocouple the actual temperature of the substance is measured. The e.m.fe.m.f. of the thermocouple varies with the centigrade temperature as follows: e.m.f. = (0.2 t − 5 × 10⁻⁴ × t²) mV.

The given thermometer is calibrated with the freezing point and the boiling point of water. If the thermocouple reads e.m.f. 105 m V in the blast furnace, then what is the temperature of the blast furnace in degree centigrade?

A
105°C

B
700°C

C
157.5°C

D
1700°C

Solution

At t = 0, e.m.f. = 0

At t = 100, e.m.f. = (20 − 5 × 10⁻⁴ × 10⁴) mV

= 15 mV

∴ rise in 100°C corresponds to e.m.f. = 15 mV

∴ 105 mV e.m.f. corresponds to rise in temperature 700°C
Question 4
4 / -1

During the electrolysis of solution of AgNO₃, 9650 C charge was passed through the electroplating bath, then the mass of silver deposited on the cathode is

A
1.08 g

B
10.8 g

C
21.6 g

D
108 g

Solution

Ag⁺+ e⁻ → Ag

9650 C = 0.1 F = 0.1 eq Ag

= 0.1 mol Ag = 10.8 g Ag
Question 5
4 / -1

The number of electrons delivered at the cathode during electrolysis by a current of 1 ampere in 60 seconds is (charge on electron = 1.60 × 10⁻¹⁹ C = 1.60 × 10^-19 C)

A
6 × 10²³

B
6 × 10²⁰

C
3.75 × 10²⁰

D
7.48 × 10²³

Solution
Question 6
4 / -1

For the second period elements the correct increasing order of first ionization enthalpy is

A
L i < Be < B < C < O < N < F < Ne

B
Li < Be < B < C < N < O < F < Ne

C
Li < B < Be < C < O < N < F < Ne

D
Li < B < Be < C < N < O < F < Ne

Solution

As we move across a period, ionisation enthalpy increases, because of increased nuclear charge and decrease in atomic radii. However, abnormal values are observed for Be, N and Ne due to extra stability of half filled and fully filled orbitals. Thus, the actual order is, Li < B < Be < C < O < N < F < Ne
Question 7
4 / -1

Which of the following oxides is most acidic in nature?

A
MgO

B
BeO

C
BaO

D
CaO

Solution

In metals, on moving down the group, metallic character increases, so basic nature increases hence most acidic will be BeO.
Question 8
4 / -1

The element Z = 114 has been discovered recently. It will belong to which of the following family/group and electronic configuration?

A
Carbon family, [Rn]5f¹⁴6d¹⁰7s²7p²

B
Oxygen family, [Rn] 5f¹⁴6d¹⁰7s²7p⁴

C
Nitrogen family, [Rn] 5f¹⁴6d¹⁰7s²7p⁶

D
Halogen family, [Rn] 5f¹⁴6d¹⁰7s²7p⁵

Solution

The electronic configuration of the element with Z = 114 (Flerovium) is [Rn]5f¹⁴6d¹⁰7s²7p²

Hence, it belongs to carbon family which has the same outer electronic configuration.
Question 9
4 / -1

The species Ar, K⁺ and Ca²⁺ contain the same number of electrons. In which order do their radii increase?

A
Ca²⁺ < K⁺ < Ar

B
K⁺< Ca²⁺<Ar

C
Ar < K⁺ < Ca²⁺

D
Ca²⁺ < Ar < k⁺

Solution

In case of isoelectronic species, radius decreases with increase in nuclear charge.
Question 10
4 / -1

Which one of the following arrangements represents the correct order of least negative to most negative electron gain enthalpy for C, Ca, Al, F and O?

A
Al < Ca < O < C < F

B
Al < O < C < Ca < F

C
C < F < O < Al < Ca

D
Ca < Al < C< O< F
Solution
1. Calcium (Ca): Least negative (often positive)
2. Aluminum (Al): Slightly negative
3. Carbon (C): More negative than Al
4. Oxygen (O): More negative than C
5. Fluorine (F): Most negative
Conclusion:

The correct order from least negative to most negative electron gain enthalpy is:

Ca < Al < C < O < F

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Chemistry Test 207

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Chemistry Test 207

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SHARING IS CARING

Question 1

Copper

Mercury

Iron

Aluminium

Solution

Question 2

Sugar

Sodium acetate

Sodium chloride

Sodium bromide

Solution

Question 3

105°C

700°C

157.5°C

1700°C

Solution

Question 4

1.08 g

10.8 g

21.6 g

108 g

Solution

Question 5

6 × 1023

6 × 1020

3.75 × 1020

7.48 × 1023

Solution

Question 6

L i < Be < B < C < O < N < F < Ne

Li < Be < B < C < N < O < F < Ne

Li < B < Be < C < O < N < F < Ne

Li < B < Be < C < N < O < F < Ne

Solution

Question 7

MgO

BeO

BaO

CaO

Solution

Question 8

Carbon family, [Rn]5f146d107s27p2

Oxygen family, [Rn] 5f146d107s27p4

Nitrogen family, [Rn] 5f146d107s27p6

Halogen family, [Rn] 5f146d107s27p5

Solution

Question 9

Ca2+ < K+ < Ar

K+< Ca2+<Ar

Ar < K+ < Ca2+

Ca2+ < Ar < k+

Solution

Question 10

Al < Ca < O < C < F

Al < O < C < Ca < F

C < F < O < Al < Ca

Ca < Al < C< O< F

Solution

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6 × 10²³

6 × 10²⁰

3.75 × 10²⁰

7.48 × 10²³

Carbon family, [Rn]5f¹⁴6d¹⁰7s²7p²

Oxygen family, [Rn] 5f¹⁴6d¹⁰7s²7p⁴

Nitrogen family, [Rn] 5f¹⁴6d¹⁰7s²7p⁶

Halogen family, [Rn] 5f¹⁴6d¹⁰7s²7p⁵

Ca²⁺ < K⁺ < Ar

K⁺< Ca²⁺<Ar

Ar < K⁺ < Ca²⁺

Ca²⁺ < Ar < k⁺