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Bromine is an element with two isotopes, with mass numbers $79$ and $81$ . Its relative atomic mass is often given as $80$ . What does that tell you about the relative abundance of the two isotopes?

Important Questions on Reacting Masses and Chemical Equations

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Chemistry>Inorganic Chemistry>Reacting Masses and Chemical Equations>The Masses of Atoms, Molecules and Ions

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>Inorganic Chemistry>Reacting Masses and Chemical Equations>The Masses of Atoms, Molecules and Ions

Calculate:

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

HARD

Chemistry>Inorganic Chemistry>Reacting Masses and Chemical Equations>The Masses of Atoms, Molecules and Ions

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>Inorganic Chemistry>Reacting Masses and Chemical Equations>The Masses of Atoms, Molecules and Ions

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>Inorganic Chemistry>Reacting Masses and Chemical Equations>The Masses of Atoms, Molecules and Ions

Calculate:

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

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Chemistry>Inorganic Chemistry>Reacting Masses and Chemical Equations>The Masses of Atoms, Molecules and Ions

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 :

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Chemistry>Inorganic Chemistry>Reacting Masses and Chemical Equations>The Masses of Atoms, Molecules and Ions

If we consider

1 / 6

, in place of

1 / 12

of mass of carbon atom as relative atomic mass unit, the mass of one mole of substance will

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Chemistry>Inorganic Chemistry>Reacting Masses and Chemical Equations>The Masses of Atoms, Molecules and Ions

A sample of copper sulphate pentahydrate contains

8.64

g of oxygen. How many gram of Cu is present in this sample?

(Atomic mass of Cu =

63.6

, S =

32.06

, O =

16

)

EASY

Chemistry>Inorganic Chemistry>Reacting Masses and Chemical Equations>The Masses of Atoms, Molecules and Ions

The average atomic mass of a mixture containing

79 m o l e %

{}^{24}{M g}

remaining

21 m o l e %

{}^{25}{M g}

and

{}^{26}{M g}

24.31 %

. Mole of

{}^{26}{M g}

is -

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Chemistry>Inorganic Chemistry>Reacting Masses and Chemical Equations>The Masses of Atoms, Molecules and Ions

Boron has two stable isotopes.

^{10} B (19 %) and^{11} B (81 %) .

Average atomic weight for boron in the periodic table is

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Chemistry>Inorganic Chemistry>Reacting Masses and Chemical Equations>The Masses of Atoms, Molecules and Ions

Number of atoms of He in 100 u of He (atomic weight of He is 4) are

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Chemistry>Inorganic Chemistry>Reacting Masses and Chemical Equations>The Masses of Atoms, Molecules and Ions

Define: gram-atomic mas.

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Chemistry>Inorganic Chemistry>Reacting Masses and Chemical Equations>The Masses of Atoms, Molecules and Ions

8

g of a radioactive isotope has a half-life of

10

hrs, then the half-life of

2

g of the same substance is

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Chemistry>Inorganic Chemistry>Reacting Masses and Chemical Equations>The Masses of Atoms, Molecules and Ions

Which of the following has smallest mass?

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Chemistry>Inorganic Chemistry>Reacting Masses and Chemical Equations>The Masses of Atoms, Molecules and Ions

Number of atoms of He in

100

u of He (atomic weight of He is

4

) are

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Chemistry>Inorganic Chemistry>Reacting Masses and Chemical Equations>The Masses of Atoms, Molecules and Ions

An element,

X

has the following isotopic composition

^{200} X : 90 %

^{199} X : 8.0 %

^{202} X : 2 .0 %

The weighted average atomic mass of the naturally occurring element

X

is closed to

EASY

Chemistry>Inorganic Chemistry>Reacting Masses and Chemical Equations>The Masses of Atoms, Molecules and Ions

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

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Chemistry>Inorganic Chemistry>Reacting Masses and Chemical Equations>The Masses of Atoms, Molecules and Ions

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

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Chemistry>Inorganic Chemistry>Reacting Masses and Chemical Equations>The Masses of Atoms, Molecules and Ions

Average atomic mass of magnesium is

24.32

amu. This Mg is composed of

79

mole % of ²⁴Mg and remaining

21

mole % of ²⁵Mg and ²⁶Mg. Calculate the mole % of ²⁵Mg?

EASY

Chemistry>Inorganic Chemistry>Reacting Masses and Chemical Equations>The Masses of Atoms, Molecules and Ions

One atom of an element

X

weighs 6.643

\times 10^{- 23}

g. Number of moles of atom in 20 kg is

Bromine is an element with two isotopes, with mass numbers 79 and 81. Its relative atomic mass is often given as 80. What does that tell you about the relative abundance of the two isotopes?

Important Questions on Reacting Masses and Chemical Equations

Learn and Prepare for any exam you want !

Bromine is an element with two isotopes, with mass numbers $79$ and $81$ . Its relative atomic mass is often given as $80$ . What does that tell you about the relative abundance of the two isotopes?