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Correct answer is Helium

Keibul Lamjao in Manipur

Harris Shield

The correct answer is Sulphur.

• The sulphur is the eye irritating compound that is released when cutting onions.
• The syn-Propanethial-S-oxide is the chemical irritant produced by an onion.
• This chemical stimulates the eyes' lachrymal glands which release tears.
• Previously scientists used to blame enzyme alinase for the instability of substances in a cut onion.
• In 2002, a study in Japan proved that lachrymatory factor synthase is responsible for irritation of the eyes.

Hyperconjugation involves delocalization of σ and π bonds orbitals. ie it undergoes σ−π conjugation. The kind of delocalization involving sigma electrons of single bond and π- electrons of multiple bond is called hyperconjugation. Hence b is the correct answer.

(d) Bases turn pink when a drop of phenolphthalein is added to them.

• Copper sulfate CuSO₄ .5H₂O – blue, 
• Copper nitrate Cu(NO₃)₂ .6H₂O – pink. 
• Potassium permanganate KMnO₄ – violet. 
• Ferrous sulfate FeSO₄ .7H₂O – Green, 
• Ferrous nitrate (Fe(NO₃)₂ .6H₂O) – light green

1.  A,B

2. B, C, D

3. E

4. G

5. C, D

6. H

7. G

8. F

Correct option is (c) (i) and (ii) only

a. A – 1s² 2s² 2p⁴

B – 1s² 2s² 2p⁶

C – 1s² 2s² 2p⁶ 3s² 

D – 1s² 2s² 2p⁶ 3s² 3p⁶ 

b. B, D 

c. CA, (C₂ A₂ is simplified and written as CA)

By losing 2 electrons from 4s valence subshell

1. 2

2. 6

a. Element X has constant oxidation state. Y shows variable oxidation states. 

b. X₂₀ = 1s² , 2s² , 2p⁶ , 3s² , 3p⁶ , 4s² 

X₂₆ = 1s², 2s² , 2p⁶ , 3s² , 3p⁶ , 4s² , 3d⁶ 

Y is a transitional element. In chemical reactions only two elections in ‘ s’ subshell or besides ‘s’ subshell electrons ‘d’ sub shell electrons also take part

Half filled and completely filled subshells are most stable. Change in the electronic configuration of ₂₄Cr &, ₂₉Cu is due to .this. The electrons in these elements are arranged in such away to give these elements stability

Manganese shows different oxidation states because in manganese 4s and 3d subshell electrons take part in chemical reactions.

a.

b.

Correct option is (A) Sulfuric acid 

CaCO₃ + H₂SO₄ → CaSO₄ + H₂O + CO₂

Correct option is (1) ClO

Polar stratospheric clouds (PSCs) surfaces act as catalysts that convert more benign forms of human made chlorine into active free radicals (for example CIO, chlorine monoxide). During the return of spring sunlight these radicals destroy many ozone molecules in a series of chain reactions.

 (a) Histamine 

Histamine, stimulates the secretion of pepsin and hydrochloric acid in the stomach.

[Hint : (i) To avoid side effects caused by drug.
(ii) To have the advice for proper dose of drug.]

Correct option is (4) Sulphuric acid

 The acid rain reacts with marble, CaCO₃ of Taj Mahal 

(CaCO₃ + H₂SO₄ → CaSO₄ + H₂O + CO₂) 

causing damage to this wonderful monument that has attracted people from around the world. As a result, the monument is being slowly disfigured and the marble is getting discoloured and lustreless.

For ideal gas

PM = dRT

\((\frac{100}{760})\)M = 0.121 x 0.082 x 530

M = d x 330.296

M = 39.97 ≈ 40

Correct option is 1) Histamine

Excess of acidity (pepsin in stomach) is due to release of excess of histamine. Therefore modern synthetic drugs are antihistamines for the treatment of gastic ulcers by blocking the acid release action of histamine

[Hint : They work well even with hard water and not form any scum.]

[Hint : (i) Ranitidine (ii) Morphine]

[Hint : Cimetidine prevents the interaction of histamines with the receptors present in stomach wall.]

[Hint : (i) Antidepressant drug (ii) Analgesics and antipyretic (iii) Antihistamine]

1. Ofloxacin – Antibiotic

2. Morphine – Analgesic

3. Ampicillin – Antibiotic

4. Chloramphenicol – Antibiotic

Werner’s postulates explain the bonding in coordination compounds as follows:
(i)    A metal exhibits two types of valencies namely, primary and secondary valencies. Primary valencies are satisfied by negative ions while secondary valencies are satisfied by both negative and neutral ions. (In modern terminology, the primary valency corresponds to the oxidation number of the metal ion, whereas the secondary valency refers to the coordination number of the metal ion.
(ii)  A metal ion has a definite number of secondary valencies around the central atom.
Also, these valencies project in a specific direction in the space assigned to the definite
geometry of the coordination compound.
(iii) Primary valencies are usually ionizable, while secondary valencies are non-ionizable.

1. Co-ordination compounds metals show two types of Valencies primary and secondary 

2. Primary valencies are ionisable 

3. Secondary valencies are non-ionisable

Ligands: 

The molecules or ions which are coordinated to the central atom or ion in the coordination compound are called ligands or donor groups.

Postulates of Werner’s theory: 

a. Two types of valencies are shown by most metallic elements: 

1. Primary valence or principal valence 

2. Secondary valence. 

b. The tendency of every metal is to satisfy both primary and secondary valences. 

c. The number of secondary valence shown by each metal is fixed. 

d. The secondary valence is always directed towards fixed positions in space.

a. Metamerism (positional isomerism): Ethers having same molecular formula but different alkyl groups attached on either side of the oxygen atom are called metamers of each other. This phenomenon is called metamerism (positional isomerism).

b. Methyl n-propyl ether: 

Structure:

CH₃ – O – CH₂ – CH₂ – CH₃

IUPAC Name: 1-Methoxypropane

c. Action of hot HI on methyl n-propyl ether:

CH₃ – O – CH₂ – CH₂ – CH₃ (Methyl n-propyl ether) + 2HI (Conc.) \(\overset{Hot/373 K}\longrightarrow\) CH₃I (Methyl iodide)+ CH₃ – CH₂ – CH₂ – I (Propyl iodide)+ H₂O

Reactions involved in the preparation of potassium dichromate from chrome iron ore (chromite ore):

a. Conversion of chrome iron ore into sodium chromate (Roasting): 

4FeO.Cr₂O₃ (Chrome iron ore) + 8Na₂CO₃ (Sodium carbonate) + 7O₂ (Oxygen) → 2Fe₂O₃ (Ferric oxide) + 8Na₂CrO₄ (Sodium chromate) + 8CO₂ (Carbon dioxide)

b. Conversion of sodium chromate into sodium dichromate:

2Na₂CrO₄ (Sodium chromate) + H₂SO₄ (conc.) → Na₂Cr₂O₇ (Sodium dichromate)+ Na₂SO₄ (Sodium sulphate) + H₂O

c. Conversion of sodium dichromate into potassium dichromate:

Na₂Cr₂O₇ (Sodium dichromate) + 2KCl (Potassium chloride) → K₂Cr₂O₇ (Potassium dichromate) + 2NaCl (Sodium chloride)

(c) 6NaOH + 3Cl₂ → 5NaCl + NaClO₃ + 3H₂O

   (hot and conc.)                                                                                                        

[Hint : KI + I₂ ->  KI₃]

[Hint : Due to small size of F atom and compact 2p orbitals there are strong interelectronic repulsions in the relatively smaller 2p orbitals of fluorine. So the incoming electron does experience more repulsion in F than in Cl.]

[Hint : Formation of nascent oxygen.]

 (d)  6CaOCl₂→ Ca(ClO₃)₂ + 5CaCl₂  .

    It is autooxidation.

Correct option is (1) RSO₃H> RCOOR > RCOCI > RCONH₂

The correct order of priority of functional groups as per IUPAC is 

RSO₃H> RCOOR > RCOCI > RCONH₂

(a) SnO₂ is an amphoteric oxide because it reacts with acids as well as with bases to form corresponding salts. SnO₂ + 2H₂ SO₄ (conc) → Sn(SO₄ ) ₂ + 2H₂O , SnO₂ + 2NaOH → Na₂ SnO₃ + H₂O