EASY

Earn 100

In the nineteenth century, scientists could determine mass of one atom relative to another by experimental methods using Avogadro's hypothesis. Earlier, hydrogen was used as the reference element being the lightest atom, but the present system of atomic masses is based on carbon- $12$ as the standard and has been agreed upon in the year .

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Important Questions on Some Basic Concepts of Chemistry

EASY

Chemistry>Physical Chemistry>Some Basic Concepts of Chemistry>Atomic and Molecular Masses

What is gram atomic mass?

MEDIUM

Chemistry>Physical Chemistry>Some Basic Concepts of Chemistry>Atomic and Molecular Masses

Two elements

A

and

B

which form

0.15

moles of

A_{2} B

and

{AB}_{3}

type compounds. If one mole of each

A_{2} B

and

{AB}_{3}

weigh equally, then the atomic weight of

A

is____times of atomic weight of

B

EASY

Chemistry>Physical Chemistry>Some Basic Concepts of Chemistry>Atomic and Molecular Masses

The common isotopes of carbon are

{}^{12}C

and

{}^{13}C

. The average mass of carbon is

12.01115 amu

. What is the abundance of the

{}^{13}C

isotope?

EASY

Chemistry>Physical Chemistry>Some Basic Concepts of Chemistry>Atomic and Molecular Masses

A and B react to produce C according to the following chemical equation
$2 A + B \to 2 C$

A, B and C are the formulas for three gaseous substances. The vapour densities of A and B are 32 and 16 respectively. Find out the vapour density of C.

EASY

Chemistry>Physical Chemistry>Some Basic Concepts of Chemistry>Atomic and Molecular Masses

What will be the mass of one atom of

{}^{12}C

EASY

Chemistry>Physical Chemistry>Some Basic Concepts of Chemistry>Atomic and Molecular Masses

Calculate:

Mass of 5 gram atoms of calcium.
[Hint: Gram atoms mass: $Ca = 40 g$ ]

MEDIUM

Chemistry>Physical Chemistry>Some Basic Concepts of Chemistry>Atomic and Molecular Masses

Consider an imaginary ion

{}_{22}^{48}X^{3 -}

. The nucleus contains '

a

%

more neutrons than the number of electrons in the ion. The value of '

a

' is

EASY

Chemistry>Physical Chemistry>Some Basic Concepts of Chemistry>Atomic and Molecular Masses

In a certain mass spectrometer, an ion beam passes through a velocity filter consisting of mutually perpendicular fields E and B. The beam then enters a region of another magnetic field

B^{'}

, perpendicular to the beam. The radius of curvature of the resulting ion beam is proportional to

EASY

Chemistry>Physical Chemistry>Some Basic Concepts of Chemistry>Atomic and Molecular Masses

Calculate mass of

3.01 \times 10^{24}

atoms of an element having atomic mass

21.13

HARD

Chemistry>Physical Chemistry>Some Basic Concepts of Chemistry>Atomic and Molecular Masses

3 g

of acetic acid is added to

250 m L

0.1 M H C l

and the solution made up to

500 m L

. To

20 m L

of this solution

\frac{1}{2} m L

5 M N a O H

is added. The

p H

of the solution is ________
[Given:

p K a

of acetic acid

= 4.75,

molar mass of acetic acid

60 g / m o l, \log 3 = 0.4771

, Neglect any changes in volume]

MEDIUM

Chemistry>Physical Chemistry>Some Basic Concepts of Chemistry>Atomic and Molecular Masses

Chlorine has two naturally occurring isotopes.

^{35} C l

and

^{37} C l

. If the atomic mass if

C l

is 35.45, the ratio of natural abundance of

^{35} C l

and

^{37} C l

is closest to

EASY

Chemistry>Physical Chemistry>Some Basic Concepts of Chemistry>Atomic and Molecular Masses

The unit of atomic mass,

amu

is replaced by

u

, here

u

stands for

HARD

Chemistry>Physical Chemistry>Some Basic Concepts of Chemistry>Atomic and Molecular Masses

Natural abundances of

^{12} C

and

^{13} C

isotopes of carbon are

99 %

and

1 %

respectively. Assuming they only contributes to the molecular weight of

C_{2} F_{4}

, the percentage of

C_{2} F_{4}

having a molecular mass of

101

EASY

Chemistry>Physical Chemistry>Some Basic Concepts of Chemistry>Atomic and Molecular Masses

Calculate:

How many gram atoms of sodium is present in $115 g$ sodium?

EASY

Chemistry>Physical Chemistry>Some Basic Concepts of Chemistry>Atomic and Molecular Masses

The average molar mass of chlorine is

35.5 g {mol}^{- 1}

. The ratio of

{}^{35}{Cl}

{}^{37}{Cl}

in naturally occurring chlorine is close to :

EASY

Chemistry>Physical Chemistry>Some Basic Concepts of Chemistry>Atomic and Molecular Masses

Which symbol replaced the unit of atomic mass, amu?

EASY

Chemistry>Physical Chemistry>Some Basic Concepts of Chemistry>Atomic and Molecular Masses

One mole of dioxygen gas at

STP

is equal to

HARD

Chemistry>Physical Chemistry>Some Basic Concepts of Chemistry>Atomic and Molecular Masses

An organic compound contains

69 %

carbon and

4.8 %

hydrogen, the remainder being oxygen. Calculate the masses of carbon dioxide and water produced when

0.20 g

of this substance is subjected to complete combustion.

EASY

Chemistry>Physical Chemistry>Some Basic Concepts of Chemistry>Atomic and Molecular Masses

The element whose gram-atomic mass and gram-molecular mass are the same is-

EASY

Chemistry>Physical Chemistry>Some Basic Concepts of Chemistry>Atomic and Molecular Masses

0.228 g

of silver salt of dibasic acid gave a residue of

0.162 g

of silver on ignition, then molecular weight of the acid is

Important Questions on Some Basic Concepts of Chemistry

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