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(d) 3 – (N, N – Dimethyl amino) – 3 – methyl pentane

(c) Dopamine

(a) Histamine

(d) 2 – methyl – 2 – nitro propane

(c) fractional distillation

(a) (ii) only

(a) Both A and R are correct and R is the correct explanation of A

(d) nitro ethane

(b) Gomberg reaction

(b) (i) and (ii)

(a) Ethanol<phenol<p-nitrophenol

(b) Propane <propanal<propanol

Detailed Answer:

(a)ethanol <phenol <p-nitrophenol

(b)propane <propanal < propanol

(ii) < (iii) < (iv) < (i)

Reason :This is due to the reason that there is increase in the magnitude of intermolecular forces in this order, as polarity of C-O bond is increasing ,it’s tendency to form H-bond also increases and hence boiling point which depend on the intermolecular forces also increases.

C₆H₅CH₂ CH(OH)CH₃

(d) Dehydrogenase alcohol

(d) Dehydrogenase alcohol

(i), (iii)

(i) Br₂/water

(iii) Neutral FeCl₃

1. The full form of DOS is Disk Operating System. 

2. Windows is a series of operating systems that are designed by Microsoft. 

3. Windows is the most commonly used operating system. 

4. Apple Corporation’s registered operating system is called Mac OS. 

5. Chrome OS is an open-source operating system created by Google. 

6. Linux is an open-source, portable, multi- multiprogramming, operating system. 

7. Android is a free and open-source operating system for mobile phones provided by Google. 

8. Asha is used by Nokia phones. This is a closed source OS. 

9. Blackberry is a closed source operating system for smartphone and tablet devices. 

10. IOS is Apple’s closed source operating system for Apple’s iPhone, iPod Touch, iPad, and second-generation Apple TVs. 

11. Windows Phone is developed by Microsoft as a closed source operating system for mobile phones. 

12. Linux is used as the predominant backbone of the Internet. 

13. Ubuntu is one of the most popular GNU/Linux distributions.

Nitro group (-NO₂)

Shift of electron pair towards the substituent in a conjugate system.

1. -NO₂ 

2. -C ≡ N 

3. -Cl 

4. -F

(a) Mass of 1 mole of oxygen = 16 g
Mass of 0.2 mole of oxygen = 0.2 × 16
= 3.2 g.
(b) Mass of 1 molecule of water = 18 gm.
Mass of 0.5 mole of water = 0.5 × 18
= 9 gm.

Yes, with the help of advanced technologies we can see atoms by using electronic microscopes. A Scanning Tunnelling Microscope (STM) can be used to produce highly magnified images of surface of elements on a computer screen.

One mole of Aluminium oxide

= 2 × 27+ 3 × 16

= 54 + 48

= 102 g.

102 g of Al₂O₃ = 6.022 × 10²³ moles (aluminium oxide)

= \(\frac{6.022\times 10^{23}}{102}\times 0.051\) molecules

It means Aluminium present in 0.051 gm

= 3.011 × 10²⁰ Aluminium oxide molecules

Number of Al ions in one mole of Al₂O₃ = 2

∴ Number of Al Ions In 3.011 × 10²⁶ molecules
0.051 Al₂O₃

= 2 × 3.011 × Number of Al ions In 3.011 × 10²⁰

= 6.022 × 10²⁰.

The symbol of an element is either the first letter or the first and another letter of the English or Latin name of the element.

A) Both A and R are true

i) The number of atoms in H₂S molecule = 2 + 1=3 

ii) The number of atoms in PO_4^3- ion =1 + 4 = 5

Atomicity: The number of atoms constituting a molecule is known as its atomicity. 

i. In I₂ , there are two atoms of iodine constituting a molecule. 

Hence, the atomicity is 2 (diatomic). 

ii. In H₂S, there are two atoms of hydrogen and one atom of Sulphur constituting a molecule of H₂S. Hence, the atomicity is 3 (triatomic). 

iii. In HNO₃ , there are three atoms of oxygen, one atom of nitrogen and one atom of hydrogen sulphur constituting a molecule of HNO₃ . Hence, the atomicity is five. 

iv. In Na₂SO₄ , there are two atoms of sodium, one atom of Sulphur and four atoms of oxygen constituting a molecule of Na₂SO₄ Hence, the atomicity is seven. 

v. In S₈ , there are eight atoms of sulphur constituting a molecule. 

Hence, the atomicity is eight.

Given: 

Mass of sodium carbonate = 212g 

Sodium carbonate is Na₂CO₃ 

First, we need to calculate the number of moles of sodium carbonate we have in a 212g sample. To calculate this, we will ind the molar mass of sodium carbonate (Na₂CO₃ ): 

⇒ 2 × Molar mass of sodium + Molar mass of carbon + 3×molar mass of oxygen 

⇒ 2 × 23 + 12 + 3 × 16 

⇒ 46 + 12 + 48 

⇒ 106g/mol 

Thus, the molar mass of Na₂CO₃ is 106g/mol. 

Now we will calculate total number of moles by applying the

formula given:

Number of moles = \(\frac{Mass\,of\,sodium\,carbonae}{Molar\,mass\,of\,sodium\,carbonate}\)

 Number of moles = \(\frac{212g}{106g/mol}\)

⇒ 2 mol 

Now, we know that every mole of Na₂CO₃ have 2 moles of Na⁺ ions.Hence, total moles of Na₂CO₃ is 4 moles

Number of ions present = 6.022 × 10²³ × 4mol = 24.088 × 10²³ ions

A) 2.007 × 10²³

The reaction (i) is a type of displacement reaction as Pb displaces Cu and form a new compound PbCl₂

The reaction (ii) is a type of double displacement reaction in which exchange of ions takes place.

The reaction (iii) is a type of combination reaction in which carbon and oxygen are combined together to form a single product that is CO₂ .

The reaction (iv) is a type of exothermic reaction as the burning of natural gas (CH₄ ) releases a large amount of energy

C) Law of conservation of mass

B) Wilhelm Ostwald

Correct option is D) Carbon

The symbols of a few elements like sodium do not start with the initial letter
of the name because their symbol was derived from their names in Latin.
For example:
i. The symbol of sodium (Na) was derived from its latin name “natrium”
ii. The symbol of potassium (K) was derived from its latin name “kalium”
iii. The symbol of iron (Fe) was derived from its latin name “ferrum”

An atom is the smallest particle of an element that can retain all the chemical properties. It is the indivisible unit of matter that can exist independently. It is building block of matter.

Correct option is A) 0.3

We know, 1 mole = 6.022 × 10²³ (Na = Avogadro’s number) 

The number of moles = \(\frac{Given\,number\,of\,atoms}{Avogadro's\,number}\)

Number of moles = \(\frac{12.044\times10^{23}}{6.022\times10^{23}}\)

Number of moles = 2 

Thus, number of moles of He is 2.

C) John Berzelius

बिन्दु P पर धारा i₁ = बिन्दु P की ओर आने वाली धाराओं का योग – बिन्दु P से दूर जाने वाली धाराओं का योग 

i₁ = 2 + 2 – 1 = 3 A बिन्दु Q पर धारा 

i₂ = i₁ – 1 A = 3 – 1 = 2 A 

बिन्दु R पर धारा i₂ + 1 A = i + 1.2 A 

i = (2 + 1 – 1.2) A = 1.8 A

दिया है, (i) जब = 0.5 ऐम्पियर तब V = 1.8 वोल्ट तथा 

(ii) जब i = 1.0 ऐम्पियर तब 

V = 1.6 वोल्ट 

V = E – ir …..(1) 

प्रथम स्थिति में समी० (1) से, 

1.8 = E – (0.5) ….. (2) 

द्वितीय स्थिति में समी० (1) से 

1.6 = E – (1.0) r …..(3) 

समी० (2) व (3) को हल करने पर, 

सेल का आन्तरिक प्रतिरोध r = 0.4 Ω विद्युत वाहक बल 

E = 2.0 वोल्ट

अर्द्धचालक- जर्मेनियम तथा सिलिकॉन।

The chemical formula of a compound is a symbolic representation of its composition.

In the given reaction,

3MnO₂ (s) + 4Al(s) → 3Mn(ℓ) + 2Al₂O₅ (s) + Heat 

Aluminum being more reactive displaces the manganese metal and forms a new compound. Hence it is a displacement reaction.

The heat is also released along with the formation of products, hence it is an exothermic reaction.

The combining power or capacity of an element is known as valency. It can be used to ind out how the atoms of an element will combine with the atoms of another element to form a chemical compound.

Importance of valency:

i. The combining power of an element is known as its valency.

ii. Valency can be used to find out how the atoms of an element will combine with the atoms of another element to form a compound.

1. Al₂(SO₄)₃: Aluminium sulphate

2. CaCl₂: Calcium chloride

3. K₂SO₄: potassium sulphate

4. KNO₃: potassium nitrate

5. CaCO₃: calcium carbonate

The number of times one atom of given element is heavier than 1/12th part of atomic mass of carbon -12 is called its atomic mass.

Lichen: Rock Moss.

Molecule 

• A molecule is a group of two or more atoms which are chemically bonded with each other. 

• A molecule is the smallest particle of matter (except element) which is capable of an independent existence and show all properties of that substance. 

E.g., ‘H₂O’ is the smallest particle of water which shows all the properties of water.

Correct option is D) Au