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Archives is the place where historical documents are preserved. The National Archives of India (NAI) is located in New Delhi. It is the chief storehouse of the records of the government of India

Correct option is (c) Grama

 Correct Option is (D) Haritalyanga in Bilaspur district of Himachal Pradesh.

 Correct Option is (D) Cro-Magnon

 Correct Option is (B) CO₂

(B)  CH₃CH₂Li + D₂O

(D)   CH₃CH₂D

(D) OH^- is a stronger base than OR^-

(D)  Ethane < ethene < ethyne 

Number of neutrons = A - Z =7 - 3 = 4

Because there is an uncertainty in the velocity of moving electron around the nucleus (Heisenberg’s Uncertainty Principle).

Because there is an uncertainty in the velocity of moving electron around the nucleus (Heisenberg's principle).

Robert Millikan oil drop experiment.

Robert Millikan.

Nucleus was discovered by Rutherford in the alpha particle scattering experiment.

E. Goldstein.

1.672 x 10²⁷ kg(1.00728 amu)

Positive charge.

Answer is Centrifugation.

1.61.6*10¹⁹ C.

9.108 × 10³¹ kg (0.0005487 amu).

We know that,

Atomic number = Number of protons = 9.

Hence, 9p

Mass number = Number of protons + Number of neutrons

⇒ 19 = 9 + Number of neutrons

⇒ Number of neutrons = 19-9 =10

Hence, 10n

Now, Number of electrons = Number of protons

⇒ Number of electrons =9

Hence, 9e

Therefore, the correct option is B

J.J. Thomson

Electron, Proton & Neutron.

The alkyl group in alcohols has + I effect due to which electron density is increases on Oxygen atom which makes the release of hydrogen ion more difficult from alcohol. R → O →H

100 cm³ of the gas weighs 0.48 grams at STP 

22,400 cm³ weight Mol. wt. at STP. 

∴ 22400/100 × 0.48 = 107.52

(i), (iv)

(i) CO²⁺

^{(iv) Cr3+}

Cr (24) = 3d⁵4s¹

Configuration . of Cr⁺³ = 3d⁴

As Cr⁺³ has stable t³_2g configuration so Cr⁺² has a tendency to change to Cr⁺³ hence it is a reducing agent.

Mn (25) =3d⁵4s²

Mn⁺³ = 3d⁴

Mn⁺³ changes to Mn⁺³ (3d)⁵ which is half filled state configuration. Hence Mn⁺³ acts as oxidising agent.

The atomic weight of an element is the ratio of average mass of an atom of an element to 1/12 of mass of an atom of C-12 Isotope.

Equivalent weight = Atomic Weight/Valency

(ii) CuF₂ compounds will be coloured in solid state.

Equivalent weight The number of parts by weight of the substance which combine or displace directly or indirectly 1.008 parts by weight of hydrogen or 8 parts by weight of oxygen or 35.5 parts by weight of chlorine or 108 parts by weight of silver.

It is defined as “ The ratio of mass of 1 molecule of the substance to mass of an atom of C-12 isotope”.

Correct Answer is: (A) time^-1 

• Oxide Method 

• Chloride Method 

• Hydrogen Displacement method 

• Inter conversion method.

It is a formula which gives the relative number of atoms of each element in the compound.

(i) Gram atom:- The atomic mass of element expressed in grams is called its gram atomic mass. It is said to be equal to one gram atom.

A gram atom of any element contains 6.023 x 10²³ atoms of the element. The gram atomic mass of an element is equal to the sum of the masses of its 6.023 x 10²³ atoms. Example: 1 gram-atom of hydrogen atom (u = 1) weighs 1 gram and contains 6.023 x 10²³ hydrogen atoms.

(ii) Gram-Mole:- The molecular mass of a substance expressed in grams is called its gram molecular mass. A gram molecular mass of substance contains 6.023 x 10²³ molecules. Example: A gram molecular mass of hydrogen molecules (molecular mass = 2) weighs 2 grams and contain 6.023 x 10²³ hydrogen molecules.

A unit is defined as the standard of reference chosen to measure any physical quantity.

The molar mass of the naturally occurring argon is equal to the weighted arithmetic mean of the various isotopes present in it. Then molar mass of argon

= {0.337 x 35.96755 g/mol + 0.063 x 37.96272 g/mol + 99.6 x 39.9624 g/mol}/{100}

= {12.121 g/mol + 2.392 g/mol + 3980.255 g/mol}/{100} = {3994.768 g/ml}/{100}

= 39.948 g/ml

Answers are:

(i) 4

(ii) 2

(iii) 2

(iv) 2

1. Internal indicator 

2. External indicator 

3. Self indicator

Molality is defined as the moles of solute per kilogram of solvent

Molality = m = {Moles of solute}/{Mass of solvent (in kg)}

= n_B/W_A = {W_B}/{M_B x W_A}

Molality of a solution does not depend on temperature.

J. J. Thomson.

Pure substances: (a) Ethyl alcohol, (b) Oxygen, (d) Carbon, (f) Distilled water. 

Mixtures: (c) Blood and (e) Steel.

Pure substances Mixtures

Pure substances: graphite, diamond, distilled water, oxygen, iron

Mixtures: milk, air, petrol, tap water, 22 carat gold, steel, wood, cloud, iodized table salt.

Correct Answer is: (A) Antacid 

Antacids contain alkaline ions that chemically neutralize stomach gastric acid, reducing damage and relieving pain. 

A substance which contains only one kind of atom or molecule is called a pure substance .