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(i) Ionisation energy:- It is the amount of energy required to remove an electron from an isolated gaseous atom. 

(ii) Electron affinity:- Electron affinity is the energy which is released when an extra electron is added to an isolated gaseous atom in its outermost shell.

(iii) Atomic radii:- The distance from the center of the nucleus to the outermost shell is defined as atomic radii. 

(iv) Modern periodic law:- Properties of the element are a periodic function of their atomic number.

In the above-mentioned elements we know that F has highest non- metallic character so it should come in the last and across the period non- metallic character increases so (b) option matches with this.

Answer: (b) Cl

Li, Be, F, N

F < N < Be < Li .

(i) The electronic configuration is 2,8. It means that the given element contains 2 electrons in K shell and 8 electrons in L shell. Thus the element contains 2 shells. Thus it belongs to the second period. Secondly, there are 8 electrons in the valence shell (completely filled) which is true for the 18^th group. 

(ii) The electronic configuration is 2,5. It means that the given element contains two shells, thus the period is 2^nd. Secondly, there are 5 electrons in the valence shell which is true for the 15^th group.

Correct option  (B) II and IV only 

Explanation: 

P (2, 8, 1) : group 1, alkali metal

Q (2,5): period 2, Group 15, valency 3

R (2,8,7):  period 3, group 17, valency 1 , non-metal

S (2, 8, 5)  period 3, group 15, valency 3, non-metal

Order of atomic number of element

A<C<B.

Because atomic size generally decreases along a period,  So B has the highest atomic number followed by C and A

When an electron is added to F, the added electron goes to the L shell (n = 2). As the ‘L’ shell possess smaller region of space, the added electron feels significant repulsion from the other electrons present in this level. 

E.A of F = -328 KJ mole^-1 

E.A of Cl = -349 KJ mole^-1 

1. The electron gain enthalpy increases as we move from left to right in a period due to the increase of nuclear charge. However, Be, Mg, N and noble gases have almost zero value of electron gain enthalpy due to extra stability of completely and half filled orbitais. 

2. When we move in a group of periodic table, the size and nuclear charge increase. But the effect of increase in atomic size is much more pronounced than that of nuclear charge and thus the additional electron feels less attraction by the large atom. Consequently, electron gain enthalpy decreases.

2, 1 ; 2, 2 ; 2,3 ; 2,4 ; 2, 5 ; 2, 6 ; 2, 7 ; 2, 8 .

(a) The horizontal rows of elements in a periodic table are called periods. As we move from left to right in a period, the atomic number of elements increases which means that the no. of protons and electrons in the atom increases. Due to large positive charge on the nucleus, the electrons are pulled in more close to the nucleus and the size of the atom decreases.

(b) (i) On moving from left to right in a period, the chemical reactivity of elements first decreases and then increases.

Example: In the 3rd period of elements, sodium is a very reactive element, magnesium is less

reactive whereas aluminium is still less reactive. Silicon is the least reactive in the third period.

Now, phosphorus is quite reactive, sulphur is still more reactive whereas chlorine is very reactive.

(ii) On moving from left to right in a period, the basic nature of oxides decreases and the acidic nature of oxides increases.

Example: In the 3rd period of the periodic table, sodium oxide is highly basic in nature and magnesium oxide is comparatively less basic. The aluminium and silicon oxides are amphoteric in nature. Phosphorus oxides are acidic, sulphur oxides are more acidic whereas chlorine oxides are highly acidic in nature.

Calcium hydroxide is used

• in the preparation of mortar, a building material.
• in white wash due to its disinfectant nature.
• in glass making and tanning industry.
• for the preparation of bleaching powder and for the purification of sugar.

(i) ammoniated electron

(c) Its salts are rarely hydrolyzed

Correct statement is beryllium salts are easily hydrolyzed

(ii) setting time of cement increases.

The addition of limited amount of water breaks the lump of lime. This process is called slaking of lime and the product is slaked lime. 

CaO + H₂O → Ca(OH)₂

Calcium oxide (quick lime) is used 

(i). to manufacture cement, mortar and glass. 

(ii). in the manufacture of sodium carbonate and slaked lime.

(iii). in the purification of sugar. 

(iv). as drying agent.

(c) milk of lime

Slaked lime Ca(OH)₂ . The suspension is called milk of lime and the clear solution is called lime water.

(i). CaO + H₂O → Ca(OH)₂ (calcium hydroxide) 

(ii). CaO + CO₂ → CaCO₃ (calcium carbonate)

Dead burnt plaster is (i) CaSO₄

(i). All the alkali metals on exposure to air burn vigorously, forming oxides on the surface of the metals. 

(ii). Lithium forms only monoxide, sodium forms the monoxide and peroxide and the other elements form monoxide, peroxide and superoxides. 

4Li + O₂ → 2Li₂O (Lithium monoxide) 

2Na + O₃ → Na₂O₂ (Sodium peroxide) 

K + O₃ → KO₂ (Potassium superoxide)

• In metallurgy, its compounds are used in pyrotechnics, petroleum mining and radiology. 
• De oxidizer in copper refining.
• Its alloys with nickel which readily emits electrons hence used in electron tubes and in spark plug electrodes.
• As a scavenger to remove last traces of oxygen and other gases in television and other electronic tubes.
• An isotope of barium ‘33Ba., used as a source in the calibration of gamma ray detectors in nuclear chemistry.

The bond orders (superoxide ion) O₂ - is 1.5 while that of(peroxide ion ) O₂ ^2- is 1.0 . Smaller the bond order, greater the bond length. Hence, O₂ ^2- has larger bond length. 

The hydration enthalpies of BeSO₄ and MgSO₄ are quite high because of small size of Be²⁺ and Mg²⁺ ions. These hydration enthalpy values are higher than their corresponding lattice enthalpies and therefore, BeSO₄ and MgSO₄ are highly soluble in water. However, hydration enthalpies of CaSO₄, SrSO₄ and BaSO₄ are not very high as compared to their respective lattice enthalpies and hence these are insoluble in water.

• Alkali metals dissolve in liquid ammonia to give deep blue solutions that are conducting in nature. 
• This happens because the alkali metal atom readily loses the valence electron in ammonia solution. 
• Both the cation and the electron combine with ammonia to form ammoniated cation and ammoniated electron. 

M + (x+v)NH₃ → [M(NH₃)_x]⁺ + [e(NH₃)_y]^-

• It is used as a common salt (or) table salt for domestic purpose. 
• It is used for the preparation of many inorganic compounds such as NaOH and Na₂CO₃ .

• Sodium is used to make Na/Pb alloy needed to make Pb(Et)₄ and Pb(Me)₄ . These organolead compounds were used as anti-knock additives to petrol in early days. 
• Liquid sodium metal is used as a coolant in fast breeder nuclear reactors.

Answer: (c) Blue

(a) superoxide and paramagnetic

RbO₂ is a super oxide which contains Rb⁺ and \(O_2^-\) ions. \(O_2^-\) contains one unpaired electron and hence it is paramagnetic.

(a) both assertion and reason are true and reason is the correct explanation of assertion

• Sodium carbonate is highly used in laundering. 
• It is an important laboratory reagent used in the qualitative analysis and in volumetric analysis. 
• It is also used in water treatment to convert the hard water to soft water. 
• It is used in the manufacture of glass, paper and paint.

(d) (i) and (ii)

(d) both assertion and reason are false

Among alkali and alkaline earth metals, K, Rb and Cs alone forms superoxides. Superoxide \(O_2^-\) has 3 electron bond.

In alkali metals, as we move down the group 

• reactivity increases 
• atomic radii increases 
• screening effect increases tendency to form cation by losing outer electron increases 
• melting point and boiling point decreases

(a) p – 2, q – 1, r – 4, s – 5, t – 6, u – 3 

(p) sodium – yellow (2) 

(p) calcium – brick red (1) 

(r) barium – apple green (4) 

(s) strontium – crimson red (5) 

(t) cesium – blue (6) 

(u) potassium – violet (3)

(i). Alkali metals have the lowest ionization enthalpy in each period. 

(ii). Within the group, as we go down, the ionization enthalpies of alkali metals decreases due to the increase in atomic size. 

(iii). In large atoms, the valence electrons are loosely held by the nucleus and arc easily lost, leading them to have low ionization enthalpy and acquiring stable noble gas configuration. 

(iv). On moving down the group, the atomic size increases and the number of inner shells also increases, which in turn increases the magnitude of screening effect. So. the ionization enthalpies decreases down the group.

The removal of one electron from the alkali metals causes the formation of monovalent cations having very stable electronic configuration. Therefore it becomes very difficult to remove the second electron from the stable noble gas configuration, giving rise to very high second ionization energy values.

(b) Statements-I and II are correct and statement-II is the correct explanation of statement-I.

(c) Transmitting nerve signals

1. Simon Commission came to India in November 1927. The Commission consisted of Sir John Simon and seven other members. All of them were members of the British Parliament.

2. Not a single India was included as a member in the Simon Commission.

3. Indians strongly believed that since the Commission was framed to bring reform, in the Indian political system, the British government must include Indian members in the Commission to understand the problems and pains of Indian society. However, the British rejected this recommendation.

4. Hence, Indians opposed the Simon Commission.

1. Even Indian youths were not happy with the Dominion Status that the British . wanted to give to India. So they also demanded complete Independence.

2. These youths met on the banks of the river Ravi in Lahore, under the leadership of Jawaharlal Nehru. There are National General Assembly passed a resolution for Complete Independence.

3. On 26th January 1930, the members took the oath of complete Independence and for the first time.

4. Since then, 26 January has become important. (Independent India has made the Republic Day (26 January) memorable by implementing the Indian Constitution on this day.

A. Dominion Freedom

The Second Round Table Conference also failed because Britishers had discriminating points for various religious committees to which Gandhiji was deeply disappointed and therefore the conference was dissolved.

The Congress working committee decided to end the individual Satyagrah because keeping in mind the world war situation, the Congress Working Committee decided to end Individual Satyagraha.

A. Mahadevbhai Desaia

1. Mahatma Gandhiji was given the responsibility to start the Civil Disobedience Movement.

2. Gandhiji made a plan to begin civil disobedience by starting a Satyagraha to protest the Salt Tax laid by the British. Hence, he decided to go to Dandi village and break the Salt Law.

3. The message of Gandhiji’s Satyagraha was delivered to people on the evening of 11th March 1930 in the assembly of about 1000 people.

4. It was also announced that even if the British arrest the satyagraha is, they should firmly maintain non-violence against the government.

5. On 12th March, 1930, Gandhiji along with 78 satyagrahis set-off for Dandi Yatra from
Ahmedabad Harijan Ashram (Sabarmati Ashram).

6. This march was 370 km long. It passed from places such as Aslali, Bareja, Nadiad, Anand, Boriavi, Ras, Jambusar, Bharuch, Surat, Navsari as well as several other small and large ragions.

7. Gandhiji and other satyagrahis explained people the reason for Civil Disobedience Movement and breaking the Salt Law.

8. Dandi Yatra created a wonderful effect in creating astonishing faith, unity and consciousness among people.

9. Gandhiji along with his colleagues and supporters reached Dandi on 5th April, 1930 after walking 24 days.

10. On the early morning of 6th April, Gandhiji broke the Salt Law by picking a handful of – salt from the sea-coast.

11. Shri Mahadevbhai Desai compared this event as ‘Mahabhiniskraman’ the great renunciation.

12. Journalists, photographers, writers and historians of India as well as of abroad visited and published reports about such a great march in their newspapers and booklets.

13. The Dandi Yatra which started from Sabarmati Ashram was praised heavily. It shook the British Empire.

14. To suppress the yatra, the British police beat the satyagrahais mercilessly. They conducted lathi charge, arrest, shooting and oppression on women and children, but people continued fearlessly.

15. During Dandi March, numerous constructive programmes like boycott of foreign clothes, prohibition of liquor, removal of untouchability, Hindu-Muslim unity and oaths to undertake social services, etc. were held.

16. Agitation done under the leadership of Abdul Ghaffar Khan (also known as Frontier Gandhi) as Vadala, Bombay.

17. Struggle against foreign liquor under the leadership of Kasturba Gandhi was suppressed in Bombay, Gharsana in Surat and in Viramgam during the Salt Law agitation.

18. Renunciation of government services, as well as removal of children from government schools, were the highlighted incidents during these movements.

C. 12th March 1930

C. Mountbatten

As a part of Civil Disobedient Movement, Gandhiji undertook the Dandi March to break the Salt Law.