What will be the mass of one C 12 atom in g ?

One mole of carbon atoms = 6.022 × 1 0 23 atoms of carbon = 12 g of carbon ∴ Mass of one C 12 atom = 12 gm 6 . 022 × 10 23 = 1 . 992 × 10 - 23 gm Thus, the required value is obtained.

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An element $X$ exists as ${}^{49}X$ and ${}^{53}X$ in nature. If atomic mass of $X$ is $50 amu$ then the mole $%$ of heavier isotope in nature, is :

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Important Questions on Some Basic Concepts of Chemistry

HARD

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

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 Mass

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 Mass

One mole of dioxygen gas at

STP

is equal to

MEDIUM

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

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 Mass

Calculate:

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

HARD

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

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

MEDIUM

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

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 Mass

Calculate mass of

3.01 \times 10^{24}

atoms of an element having atomic mass

21.13

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

Which symbol replaced the unit of atomic mass, amu?

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

The unit of atomic mass,

amu

is replaced by

u

, here

u

stands for

MEDIUM

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

A fuel cell generates electricity by using methanol as fuel and

O_{2}

as the oxidant. Calculate the equivalent weight of methanol.

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

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?

MEDIUM

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

An organic compound contains

60 % C; 4.48 % H

and

35.5 % O .

Its empirical formula is

EASY

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

What will be the mass of one atom of

{}^{12}C

EASY

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

Calculate:

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

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

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 Mass

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

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

It is known that atoms have proton, neutron, electron and nucleus. If the mass of neutron assumed to be half of its original value whereas that of proton is assumed to be twice the original value, then the atomic mass of ₆C¹⁴ will be

EASY

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

What will be the mass of one

{}^{12}C

atom in

g

MEDIUM

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

Given that the abundance of isotopes

_{54} Fe,_{56} Fe

and

_{57} Fe

are

5 %, 90 %

and

5 %

respectively, what is the atomic mass of

Fe

An element X exists as X49 and X53 in nature. If atomic mass of X is 50 amu then the mole % of heavier isotope in nature, is :

Important Questions on Some Basic Concepts of Chemistry

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An element $X$ exists as ${}^{49}X$ and ${}^{53}X$ in nature. If atomic mass of $X$ is $50 amu$ then the mole $%$ of heavier isotope in nature, is :