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If $8$ 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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Important Questions on Some Basic Concepts of Chemistry

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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?

EASY

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

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

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]

EASY

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

One mole of dioxygen gas at

STP

is equal to

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: $Ca = 40 g$ ]

EASY

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

Which symbol replaced the unit of atomic mass, amu?

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

The unit of atomic mass,

amu

is replaced by

u

, here

u

stands for

EASY

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

What will be the mass of one atom of

{}^{12}C

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.

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

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

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

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 :

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

3.011 \times 10^{22}

atoms of an element weigh

1.15 gm

. The atomic mass of the element is.

EASY

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

If we consider that

\frac{1}{6},

in place of

\frac{1}{12}

, mass of carbon atom is taken to be the relative atomic mass unit, the mass of one mole of a substance will

EASY

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

If molecular mass and atomic mass of sulphur are

256

and

32

respectively, its atomicity is

EASY

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

Number of protons, neutrons and electrons in the element

_{89}^{231} Y

If 8 g of a radioactive isotope has a half-life of 10 hrs, then the half-life of 2g of the same substance is

Important Questions on Some Basic Concepts of Chemistry

Learn and Prepare for any exam you want !

If $8$ g of a radioactive isotope has a half-life of $10$ hrs, then the half-life of $2$ g of the same substance is