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A. False

The acidic nature of oxides of group 13 decreases down the group. It changes from acidic through amphoteric to basic.

B. True

Correct answer is

D. 8

Option : (c) HF

Correct option is (A) neutron

i. True 

ii. False 

Hydrogen atom does not exist freely and is always associated with other molecules i.e.,

H₃O⁺ . 

iii. True 

iv. True

The oxides are binary compounds in which one element is oxygen and another may be a metal or a non-metal. 

They are classified as follows :

• acidic oxides, CO₂, SO₂, etc. 
• Basic oxides, CaO, BaO, etc. 
• Amphoteric oxides, Al₂O₃, ZnO, etc. 
• Neutral oxides, NO, N₂O, CO, etc. 

• All halogens react with metals instantly to give metal halides. 
• Down the group reactivity decreases from fluorine to iodine. 
• 2Na_(s) + Cl_2(I) → 2NaCl_(s), Mg_(s) + Br_2(s) → MgBr_2(s) 
• Halogens being highly electronegative, the metalhalogen bonds are ionic and ionic character decreases down the group. 

For example,

M-F > MCl > M-Br > M-I. 

• The metal halides with higher oxidation state of the metal are more covalent than the halides with lower oxidation state of metal. 

For example,

SnCl₄, PbCl₄, SbCl₅ and UF₆ are more covalent than

The thermal stability of the hydrides of group 16 elements decreases in the order of H₂O > H₂S > H₂Se > H₂Te.

(D) alkali metals

i. Hydrogen on reaction with halogens (X₂) give compounds with general formula HX.

e.g. H₂ + Cl₂ → 2HCl

ii. Similarly, alkali metals (M) on reaction with halogens (X₂) give compounds with general formula MX.

e.g. 2Na + Cl₂ → 2NaCl

iii. Thus, H₂ and alkali metals are monovalent elements and more electropositive than halogens. This similarity justifies the position of hydrogen in the group 1.

• The increased stability of the oxidation state lowered by 2 units than the group oxidation state in heavier p-block elements is due to inert pair effect.
• In these elements, the two s-electrons are involved less readily in chemical reactions.
• This is because, in heavier p-block elements, the s-electrons of valence shell experience poor shielding than valence p-electrons due to ten inner delectrons.

Hence, the increased stability of the oxidation state is lowered by 2 units than the group oxidation state in heavier p-block elements.

• Group 1 of the periodic table consists of the elements: hydrogen, lithium, sodium, potassium, rubidium, caesium and francium. 
• Group 2 of the periodic table consists of elements: beryllium, magnesium, calcium, strontium, barium and radium.

Correct option is (C) hydrogen

Hydrogen is the first element in the periodic table.

• The general oxidation states of group 13 are +1 and +3.
• The group 13 elements have the outermost electronic configuration ns² np¹.
• If only np¹ electron takes part in bonding, the oxidation state is +1 and if all the three electrons i.e., ns² np¹ take part in bonding, the oxidation state is +3. Hence, the expected oxidation states are +1 and +3.

• Elements of group 1 and group 2 in which the last electron enters into ‘ns’ subshell are s-block elements. 
• The s-block elements are placed on the extreme left in the modem periodic table.

A maximum of 6 electrons can be accommodated in the p-subshell, giving rise to six groups. In the periodic table, groups 13 to 18 include p-block elements.

• The elements of groups 13, 14 and 15 do not occur in free monoatomic state and are found as compounds with other elements.
• They also occur in the form of polyatomic molecules (such as N₂, P₄, C₆₀) or polyatomic covalent arrays (such as graphite, diamond).

(i) NH₃ (Base) + HCl (Acid) → Nh₄cl (Ammonium chloride, salt) + H₂O

When ammonia reacts with hydrochloric acid, it forms ammonium chloride and water.

(ii) CuCO₃ (Base) + H₂SO₄ (Acid) → CuSO₄ (Copper sulphate, salt)+ CO₂ + H₂O

When copper carbonate reacts with sulphuric acid, it forms copper sulphate, carbon dioxide and water.

(iii) NaOH (Base) + HCl (Acid) → NaCl (Sodium chloride, salt) + H₂O

When sodium hydroxide reacts with hydrochloric acid, it forms sodium chloride and water.

(iv) Mg(OH)₂(Base) + 2HNO₃ (Acid) → Mg(NO₃)₂ (Magnesium nitrate, salt) + 2H₂O

When magnesium hydroxide (milk of magnesia) reacts with nitric acid, it forms magnesium nitrate and water.

(v) 2KOH(Base) + H₂SO₄ (Acid) → K₂SO₄ (Potassium sulphate, salt) + 2H₂O

When potassium hydroxide reacts with sulphuric acid, it forms potassium sulphate and water.

(vi) Ca(OH)₂(Base) + 2HNO₃ (Acid) → Ca(NO₃)₂ (Calcium nitrate, salt) + 2H₂O

When calcium hydroxide reacts with nitric acid, it forms calcium nitrate and water

• The electronic configuration of oxygen is ls²2s²2p⁴. 
• It has two half filled p-orbitals and no d-orbitals for excitation of electrons. Hence it cannot show higher oxidation states. 
• Oxygen being highly electronegative, it mostly shows an oxidation state of – 2 only. 
• Other members of the family like sulphur, have vacant d-orbitals, thereby giving four and six halffilled orbitals for bonding. 
• Furthermore, they can combine with more electronegative elements. 
• Hence, they show oxidation states of +2, +4 and 4 -6 also. 

Group 16 elements : 

Oxygen (₈O); 

Sulphur (₁₆S); 

Selenium (₃₄Se); 

Tellurium(₅₂Te); 

Polonium(₈₄Po)

Group 17 elements : 

Fluorine (₉F); 

Chlorine (₁₇Cl); 

Bromine (₃₅Br); 

Iodine (₅₃I); 

Astatine (₈₅At).

Group 18 elements : 

Helium (₂He);

Neon (₂Ne), 

Argon (₁₈Ar), 

Krypton (₃₆Kr), 

Xenon(₅₄Xe), 

Radon (₈₆Rn)

The group 16 is called the oxygen family.

• Ozone due to its oxidising property can act as a bleaching agent. O_3(g) → O_2(g) + O
• It bleaches coloured matter. coloured matter + O → colourless matter
• Ozone bleaches in the absence of moisture, so it is also known as dry bleach.
• Ozone can bleach ivory and delicate fabrics like silk.

(i) Chlorine acts as a powerful bleaching agent due to its oxidising nature.

(ii) In moist conditions or in the presence of water it forms unstable hypochlorous acid, HOCl which decomposes giving nascent oxygen which oxidises the vegetable colouring matter of green leaves, flowers, litmus, indigo, etc.

Cl₂ + H₂O → HCl + HOCl 

HOCl → HCl + [O]

Vegetable coloured matter + [O] → colourless matter.

• Chlorine acts as a powerful bleaching agent due to its oxidising nature.
• In moist conditions or in the presence of water it forms unstable hypochlorous acid, HOCl which decomposes giving nascent oxygen which oxidises the vegetable colouring matter of green leaves, flowers, litmus, indigo, etc.

Cl₂ + H₂O → HCl + HOCl 

HOCl → HCl + [O]

Vegetable coloured matter + [O] → colourless matter.

As the bond is formed by sharing of electrons between two atoms. Intermolecular forces are small between the covalent compounds. These bonds break easily.

(a) Carbon cannot form C⁴⁺ cation because of removal of 4 elections from a carbon atom would require a large amount of energy.

(b) Carbon cannot form C^4- anion because it would be difficult for the nucleus with 6 protons to hold on to 10 electrons.

(c) Hence, carbon atoms share electrons forming covalent compounds.

(d) Covalent compounds do not form ions/ charged particles and therefore do not conduct electricity.

(e) Inter molecular forces of attraction are weak, hence low melting and boiling points.

Significance of the formula: 

1. A chemical formula represents its name 

2. It represents one molecule of a substance 

3. It gives the number of atoms of each element present in one molecule. 

4. It represents one mole of molecule of the substance.

O-nitrophenol is steam volatile therefore it can be separated by Steam distillation.

The process Distillation Under reduced pressure is used to purify a liquid which decomposes at its boiling point.

Law of multiple proportions: 

"When two elements combine to form two or more than two different compounds then the different masses of one element B which combine with fixed mass of the other element bear a simple ratio to one another".

Law of reciprocal proportion: 

"If two elements B and C react with the same mass of a third element (A), the ratio in which they do so will be the same or simple multiple if B and C reacts with each other".

NO₂ group has –I effect and disperse the negative charge on Oxygen atom

O₂N←CH₂← CH₂O^-

(c) If assertion is CORRECT, but reason is INCORRECT.

Correct option: (C) 1L = 10³ m³ 

1L = 10^-3 m³ = 10³ cm³ = 1dm³ = 10³ ml.

\(\because\) Number of molecules of SO₂ present in 22.4 L at STP = 6.022 × 10²³

^{\(\therefore\)} Number of molecules of SO₂ present in 11.2 L

At STP = \(\frac{6.022\times10^{23}\times11.2}{22.4}\)

= 3.011 x 10²³

(a) If both assertion and reason are CORRECT and reason is the CORRECT explanation of the assertion.

Let the length of second diagonal = d₁ cm

Then, \(\frac12\) x (d₁ x 10) = 150 ⇒ d₁ = \(\frac{150\times2}{10}\) = 30 cm.

(c) Only her lover

The general outer electronic configuration of s block elements is ns⁽¹⁻²⁾. The general outer electronic configuration of p block elements is ns²np⁽¹⁻⁶⁾. The general outer electronic configuration of d block elements is (n−1)d⁽¹⁻¹⁰⁾ns⁽⁰⁻²⁾. The general outer electronic configuration of  f− block elements is (n−2)f⁽⁰⁻¹⁴⁾(n−1)d⁽⁰⁻¹⁾ns².

The correct answer is (b) (i) and (iii)

 (d) In k = \(\frac{ΔH°}{T}-\frac{ΔS°}{R}\)

A pure substance is one which is made up of only one kind of particles. These may be atoms or molecules and can’t be separated by any physical method for example water, sulphur, hydrogen, carbon etc. are know as pure substances because they are made up of only one kind of particles. A pure substance has a fixed composition as well as a fixed melting point and boiling point.

(B) Communists

The leaders of various sections decided to unite into one large organization and thus AMS was formed in 1930.

Elements are divided into three classes i.e. metals, nonmetals and metalloids. When two or more elements combine chemically in a fixed proportion by weight, a compound is formed. The properties of a compound are altogether different from those of the constitutional elements.

The chemical reaction in which a reactant gains hydrogen and loses oxygen to form the product is called the reduction reaction.

• Atomic number of neon is 10, so its electronic configuration is (2, 8). There are 8 electrons in its 2nd shell, fulfilling its capacity. 
• Thus, neon has a complete octet. 
• It has a stable orbit therefore, it does not indulge in chemical reactions. Hence, neon is a chemically inert element.

Correct option (c) (a)-(iii), (b)-(iv), (c)-(ii), (d)-(i)   

Explanation:

Balanced chemical equation is

Fe₂O₃ + xCO → yFe + xCO₂

Thus, x is 3 and y is 2. ln this reaction, Fe₂O₃ loses oxygen so, it gets reduced and acts as an oxidising agent while CO gains oxygen so, it gets oxidised and acts as a reducing agent.