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a.

b. Group and period of the element can be identified easily. In the Same way long electron configuration can be avoided.

a. P -1s² , 2s² , 2p⁶ , 3s² , 3p⁵

Q -1s² , 2s² , 2p⁶ , 3s² 

b. Q is electropositive. P is electro negative; 

∴Chemical formula QP2

Cu¹⁺ – 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰

Cu²⁺ – 1s² 2s² 2p⁶ 3s² 3p⁶ 3d⁹

1. Complete sub shell electronic configuration: 

1s² , 2s² , 2p⁶ , 3s² , 3p⁶ , 3d⁸ , 4s² 

2. Atomic number: 28 

3. Block : d 

4. Period number: 4 

5. Group number : 8 + 2 = 10

a. 1s² , 2s² ,2p⁶ , 3s² , 3p² 

b. Is² , 2s² , 2p⁶

a. ₄Be : 1s² 2s² — s block 

b. ₂₆Fe : Is² 2s² 2p⁶ 3s² 3p⁶ 3d⁶ 4s² — d block 

c. ₁₈Ar : 1s² 2s² 2p⁶ 3s² 3p⁶ — p block

Wrong electronic configuration 

a. 1s² , 2s² , 2p⁷ (2p maximum 6 electrons only) 

c. 1s² , 2s² , 2p⁵ , 3s¹ (electrons are filled in 3s only after filling 6 electrons in 2p) 

d. 1s² , 2s² , 2p⁶ , 3s² , 3p⁶ , 3d² , 4s¹ (electrons are filled in 3d only after filling 2 electrons in 4s)

A₁₇ — 1s² 2s² 2p⁶ 3s² 3p⁵

B₂₄ — 1s² 2s² 2p⁶ 3s² 3p⁶ 3d⁵ 4s¹

1. 3

2. K — Is, L — 2s, 2p, M — 3s

3. 3s

4. 12

5. 12

6. [Ne]3s²

Answer is 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁴

a. Valence shell electrons of d-block elements in same periods are almost same. Valence shell electrons are entering in chemical reaction. Therefore they shows similarity. 

b. Energy of electrons in s-sub shell and inner d- subshells are almost same. Therefore s- electrons or s and d electrons take part in chemical reaction and show variable oxidation state.

a. B; 

b. A, C;

c. C, D; 

d. E

B[Z=5] -1s¹ 2s² 2p¹

a. [Xe] 6s¹ 

b. [Ar ] 3d² , 4s² 

c. [Ne] 3s² , 3p⁵ 

d. [Ne] 3s² ,[Ar] 3d² , 4s²

a. 1s² , 2s² , 2p⁶ , 3s² , 3p⁶ , 3d⁷ , 4s²

block – d; group – 9; period – 4. 

b. 1s² , 2s² , 2p⁶ , 3s² , 3p⁶ , 4s¹ 

block – s; group – 1; period – 4

C. 1s² , 2s² , 2p⁶ , 3s² , 3p³

block – p; group – 15; period – 3

Answer is 1s²

Be[Z=4] -1s² 2s²

Answer is 1s² 2s¹

(σ₁1s)² (σ^x1s)² (σ2s)²

Ozone, Nitric oxide, Acrolein, Frmaldehyde and peroxy acetyl nitrate.

It is ratio of number of moles of a particular component to the total number of moles of the solution. 

Mole fraction = n_B/n_A + n_B

Helium molecule has bond order equal to zero, hence molecule does not exist.

The average distance between the centres of the nucleus of the two bonded atoms in a molecule.

Higher charges lower the size.

Al³⁺ has lower size than Mg²⁺.

A bond is formed by the attraction force which holds various constituent together in different chemical species.

Water is the primary raw material which is responsible for the oxygen release during photosynthesis.

Five Characteristics of Effective School Culture

• Attention to culture is everywhere.
• A nurturing environment with high expectations.
• Engaged staff, engaged students.
• A commitment to lifelong learning.
• Holistic sense of responsibility.

Features of cultures:

1. Culture is learned

Culture is not inherited biologically but it is leant socially by man in a society. It is not an inborn tendency but acquired by man from the association of others, e.g. drinking, eating, dressing, walking, behaving, reading are all learnt by man.

2. Culture is social

It is not an individual phenomena but it is the product of society. It develops in the society through social interaction. It is shared by the man of society No man can acquire it without the association of others. Man is man only among men. It helps to develop qualities of human beings in a social environment. Deprivation of a man from his company is the deprivation of human qualities.

3. Culture is shared

Culture is something shared. It is nothing that an individual can passes but shared by common people of a territory. For example, customs, traditions, values, beliefs are all shared by man in a social situation. These beliefs and practices are adopted by all equally.

4. Culture is transmitted

Culture is capable of transmitted from one generation to the next. Parents papas cultural traits to their children and in return they pass to their children and son on. It is not transmitted through genes but through language. Language is means to communication which passes cultural traits from one generation to another.

5. Culture is continuous

It is continuous process. It is like a stream which is flowing from one generation to another through centuries. “Culture is the memory of human race.”

6. Culture is accumulative

Culture is not a matter of month or a year. It is the continuous process and adding new cultural traits. Many cultural traits are borrowed from out side and these absorbed in that culture which adopt it, as culture is accumulative and combines the suitable cultural traits.

7. Culture is integrated

All the cultural aspects are inter-connected with each other. The development of culture is the integration of its various parts. For example, values system is interlinked with morality, customs, beliefs and religion.

C. National resources

The correct option is (B) both A and C are true.

There are many activities that are undertaken by directly using natural resources. For example, the cultivation of cotton. Cotton production depends mainly (though not entirely) on natural factors like rainfall, sunshine and climate. So cotton is a natural product. Basic dairy products, minerals and ores are also natural products. When we produce a good by exploiting natural resources, it is an activity of primary sector. This is because it forms the base for all other products that we subsequently make. Since most of the natural products are from agriculture, dairy, fishing, forestry, this sector is also called agriculture and related sector.

The correct option is (B) both A and C are true.

There are many activities that are undertaken by directly using natural resources. For example, the cultivation of cotton. Cotton production depends mainly (though not entirely) on natural factors like rainfall, sunshine and climate. So cotton is a natural product. Basic dairy products, minerals and ores are also natural products. When we produce a good by exploiting natural resources, it is an activity of primary sector. This is because it forms the base for all other products that we subsequently make. Since most of the natural products are from agriculture, dairy, fishing, forestry, this sector is also called agriculture and related sector.

Private schools come under unorganised sector as it is owned by individuals privately other than govt. It is not belongs to organised sector becase in that sector institutions or organisations were under the control of government.

(C) Charge on the surface of colloidal particles

The potential difference between the fixed and diffused layer of charges in a colloidal particle is called zeta potential

(B) Both A and R are correct. but R is NOT the correct explanation of A.

Yes, Mg have lower MP and BP than aluminium but it does not explain the above fact.

The correct option is (b) CaSO₄.1/2H₂O.

The chemical name of plaster of Paris is calcium sulphate hemihydrate because half molecule of water is attached with calcium sulphate.

The chemical formula of plaster of Paris is CaSO₄.1/2H₂O.

Plaster of paris is a white powder.

It is used for many purposes like making toys, immobilizing the fractured bones.

Correct option is (c) 3s²3p⁴

E selenium (Se) 

Element present above Se is sulphur. Valence shell electronic configuration of sulphur is [Ne]3s²3p⁴

CaSO₄. 1/2H₂O

(i) 1s² 2s² 2p⁶ 3s² 3p⁶, 4s¹ 3d⁵ 

(ii) n = 4, l = 0 

(iii) Six or 6.

The ionization enthalpy of an atom depends on the number of electrons and protons (nuclear charge) of that atom. Now, the isotopes of an element have the same number of protons and electrons. Therefore, the first ionization enthalpy for two isotopes of the same element should be the same.

The first ionization enthalpy of sodium is more than that of magnesium. This is primarily because of two reasons:
a. The atomic size of sodium is greater than that of magnesium
b. The effective nuclear charge of magnesium is higher than that of sodium
For these reasons, the energy required to remove an electron from magnesium is more than the energy required in sodium. Hence, the first ionization enthalpy of sodium is lower than that of magnesium.
However, the second ionization enthalpy of sodium is higher than that of magnesium. This is because after losing an electron, sodium attains the stable noble gas configuration. On the other hand, magnesium, after losing an electron still has one electron in the 3s-orbital. In order to attain the stable noble gas configuration, it still has to lose one more electron. Thus, the energy required to remove the second electron in case of sodium is much higher than that required in case of magnesium. Hence, the second ionization enthalpy of sodium is higher than that of magnesium.

(i) During the process of ionization, the electron to be removed from beryllium atom is a 2s-electron, whereas the electron to be removed from boron atom is a 2p-electron.
Now, 2s-electrons are more strongly attached to the nucleus than 2p-electrons. Therefore, more energy is required to remove a 2s-electron of beryllium than that required to remove a 2p-electron of boron. Hence, beryllium has higher ΔiH than boron.
(ii) In nitrogen, the three 2p-electrons of nitrogen occupy three different atomic orbitals. However, in oxygen, two of the four 2p-electrons of oxygen occupy the same 2p-orbital. This results in increased electron-electron repulsion in oxygen atom. As a result, the energy required to remove the fourth 2p-electron from oxygen is less as compared to the energy required to remove one of the three 2p-electrons from nitrogen. Hence, oxygen has lower ΔiH than nitrogen.
Fluorine contains one electron and one proton more than oxygen. As the electron is being added to the same shell, the increase in nuclear attraction (due to the addition of a proton) is more than the increase in electronic repulsion (due to the addition of an electron). Therefore, the valence electrons in fluorine atom experience a more effective nuclear charge than that experienced by the electrons present in oxygen. As a result, more energy is required to remove an electron from fluorine atom than that required to remove an electron from oxygen atom. Hence, oxygen has lower ΔiH than fluorine.

(i) O and F are present in the same period of the periodic table. An F atom has one proton and one electron more than O and as an electron is being added to the same shell, the atomic size of F is smaller than that of O. As F contains one proton more than O, its nucleus can attract the incoming electron more strongly in comparison to the nucleus of O atom. Also, F needs only one more electron to attain the stable noble gas configuration. Hence, the electron gain enthalpy of F is more negative than that of O.
(ii) F and Cl belong to the same group of the periodic table. The electron gain enthalpy usually becomes less negative on moving down a group. However, in this case, the value of the electron gain enthalpy of Cl is more negative than that of F. This is because the atomic size of F is smaller than that of Cl. In F, the electron will be added to quantum level n = 2, but in Cl, the electron is added to quantum level n = 3. Therefore, there are less electron- electron repulsions in Cl and an additional electron can be accommodated easily. Hence, the electron gain enthalpy of Cl is more negative than that of F.

(i) Since n = 3, the element belongs to the 3rd period. It is a p–block element since the last electron occupies the p–orbital.
There are four electrons in the p–orbital. Thus, the corresponding group of the element
= Number of s–block groups + number of d–block groups + number of p–electrons
= 2 + 10 + 4
= 16

Therefore, the element belongs to the 3rd period and 16th group of the periodic table.
Hence, the element is Sulphur.
(ii) Since n = 4, the element belongs to the 4th period. It is a d–block element as d– orbitals are incompletely filled.
There are 2 electrons in the d–orbital.
Thus, the corresponding group of the element
= Number of s–block groups + number of d–block groups
= 2 + 2 = 4
Therefore, it is a 4th period and 4th group element. Hence, the element is Titanium.
(iii) Since n = 6, the element is present in the 6th period. It is an f –block element as the last electron occupies the f–orbital. It belongs to group 3 of the periodic table since all f-block elements belong to group 3. Its electronic configuration is [Xe] 4f7 5d1 6s2.
Thus, its atomic number is 54 + 7 + 2 + 1 = 64. Hence, the element is Gadolinium.

The elements present in group 1 have only 1 valence electron, which they tend to lose. Group 17 elements, on the other hand, need only one electron to attain the noble gas configuration. On moving down group 1, the ionization enthalpies decrease. This means that the energy required to lose the valence electron decreases. Thus, reactivity increases on moving down a group. Thus, the increasing order of reactivity among group 1 elements is as follows:

Li < Na < K < Rb < Cs
In group 17, as we move down the group from Cl to I, the electron gain enthalpy becomes less negative i.e., its tendency to gain electrons decreases down group 17. Thus, reactivity decreases down a group. The electron gain enthalpy of F is less negative than Cl. Still, it is the most reactive halogen. This is because of its low bond dissociation energy. Thus, the decreasing order of reactivity among group 17 elements is as follows: 

F > Cl > Br > I

Correct option is B) line

1. The metallic character decreases from left to right across the period due to increase in ionization enthalpy along a period which makes loss of electrons difficult. From top to bottom a group metallic character increases due to decrease in ionization enthalpy. Thus, metallic character decreases diagonally from left bottom to right top of the periodic table.

2. Acidic oxides: CO₂ , Cl₂O₇

Basic oxides: Na₂O, MgO

Neutral oxides: CO, N₂O

Amphoteric oxides: Al₂O₃, As₂O₃ 

1. Helium 

2. Yes 

3. Strictly, helium belongs to the s-block but its positioning in the p-block along with other group 18 elements is justified because it has a completely filled valence shell (1s²) and as a result, exhibits characteristic of other noble gases.