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5 g sample contain only Na₂CO₃ and Na₂SO₄ . This sample is dissolved and the volume made up to 250 mL, 25 mL of this solution neutralizes 20 mL of 0.1 M H₂SO₄ . Calculate the % of Na₂SO₄ in the sample :

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Important Questions on Some Basic Concepts of Chemistry

EASY

Chemistry>Physical Chemistry>Some Basic Concepts of Chemistry>Percentage Composition of Compounds

Calculate the percentage by weight of oxygen in a mole of water?

EASY

Chemistry>Physical Chemistry>Some Basic Concepts of Chemistry>Percentage Composition of Compounds

The percentage composition of carbon by mole in methane is:

EASY

Chemistry>Physical Chemistry>Some Basic Concepts of Chemistry>Percentage Composition of Compounds

In an estimation of bromine by Carius method,

1.6 g

of an organic compound gave

1.88 g

AgBr

. The mass percentage of bromine in the compound is

\dots . .

(

Atomic mass,

Ag = 108, Br = 80 {gmol}^{- 1}

EASY

Chemistry>Physical Chemistry>Some Basic Concepts of Chemistry>Percentage Composition of Compounds

In the crystalline solid

M S O_{4} \cdot n {II}_{2} O

of molar mass

250 g {mol}^{- 1},

the percentage of anhydrous salt is

64

by weight. The value of

n

EASY

Chemistry>Physical Chemistry>Some Basic Concepts of Chemistry>Percentage Composition of Compounds

Mass % of carbon in ethanol is

MEDIUM

Chemistry>Physical Chemistry>Some Basic Concepts of Chemistry>Percentage Composition of Compounds

A metal

M

(specific heat

0.16

) forms a metal chloride with

65 %

chlorine present in it. The formula of the metal chloride will be

MEDIUM

Chemistry>Physical Chemistry>Some Basic Concepts of Chemistry>Percentage Composition of Compounds

Complex A has a composition of

H_{12} O_{6} {Cl}_{3} C r

. If the complex on treatment with conc.

H_{2} {SO}_{4}

loses

13.5 %

of its original mass, the correct molecular formulas of

A

is:
[Given : atomic mass of

C r = 52

amu and

Cl = 35

amu]

HARD

Chemistry>Physical Chemistry>Some Basic Concepts of Chemistry>Percentage Composition of Compounds

In a non-stoichiometric sample of cuprous sulphide, with the composition ${Cu}_{1.8} S,$ cupric ions are also present in the lattice. What mole percent of ${Cu}^{2 +}$ is present in the copper content of the crystal?

HARD

Chemistry>Physical Chemistry>Some Basic Concepts of Chemistry>Percentage Composition of Compounds

1.85 g

sample of an arsenic-containing pesticide was chemically converted to

{AsO}_{4}^{3 -}

(atomic mass of

As = 74.9

) and titrated with

{Pb}^{2 +}

to form

{Pb}_{3} {({AsO}_{4})}_{2}

. If

20 mL of 0.1 M {Pb}^{2 +}

is required to reach the equivalence point, the mass percentages of arsenic in the pesticide sample is closest to

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Chemistry>Physical Chemistry>Some Basic Concepts of Chemistry>Percentage Composition of Compounds

One mole of one of the sodium salts listed below, having carbon content close to

14.3 %

produces

1

mole of carbon dioxide upon heating

(Atomic masses : Na = 23, H = 1, C = 12, O = 16)

. The salt is

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Chemistry>Physical Chemistry>Some Basic Concepts of Chemistry>Percentage Composition of Compounds

Complete combustion of

750 g

of an organic compound provides

420 g

{CO}_{2}

and

210 g

H_{2} O

. The percentage composition of carbon and hydrogen in organic compound is

15.3

and ______ respectively. (Round off to the Nearest Integer)

MEDIUM

Chemistry>Physical Chemistry>Some Basic Concepts of Chemistry>Percentage Composition of Compounds

A sample of a hydrate of barium chloride weighing 61 g was heated until all the water of hydration is removed. The dried sample weighed 52 g. The formula of the hydrated salt is: (atomic mass, Ba = 137 amu, Cl = 35.5 amu)

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Chemistry>Physical Chemistry>Some Basic Concepts of Chemistry>Percentage Composition of Compounds

When $0.15 g$ of an organic compound was analyzed using Carius method for estimation of bromine, $0.2397 g$ of $AgBr$ was obtained. The percentage of bromine in the organic compound is _________.(Nearest integer)

[Atomic mass : Silver $= 108,$ Bromine $= 80$ ]

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Chemistry>Physical Chemistry>Some Basic Concepts of Chemistry>Percentage Composition of Compounds

1 g

of an organic compound containing

C

and

H

, on complete combustion produced

3.04 g

{CO}_{2}

and

1.53 g

H_{2} O

. Find the approximate percentage composition of

C

and

H

in the compound.

MEDIUM

Chemistry>Physical Chemistry>Some Basic Concepts of Chemistry>Percentage Composition of Compounds

Among the following nitrogen compounds, which one has lowest percentage of nitrogen?

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Chemistry>Physical Chemistry>Some Basic Concepts of Chemistry>Percentage Composition of Compounds

$116 g$ of a substance upon dissociation reaction, yields $7.5 g$ of hydrogen, $60 g$ of oxygen and $48.5 g$ of carbon. Given that the atomic masses of $H, O$ and $C$ are $1, 16$ and $12$ , respectively. The data agrees with how many formulae of the following?

A. ${CH}_{3} COOH$

B. $HCHO$

C. ${CH}_{3} {OOCH}_{3}$

D. ${CH}_{3} CHO$

MEDIUM

Chemistry>Physical Chemistry>Some Basic Concepts of Chemistry>Percentage Composition of Compounds

A protein '

A

' contains

0.30 %

of glycine (molecular weight

75

). The minimum molar mass of the protein '

A

' is____

\times 10^{3} g {mol}^{- 1}

[nearest integer]

HARD

Chemistry>Physical Chemistry>Some Basic Concepts of Chemistry>Percentage Composition of Compounds

An organic compound contains

C, H

and

S

. The minimum molecular weight of the compound containing

8 %

Sulphur is

EASY

Chemistry>Physical Chemistry>Some Basic Concepts of Chemistry>Percentage Composition of Compounds

The percentage of nitrogen by mass in ammonium sulphate is closest to (atomic masses H = 1, N = 14, O = 16, S = 32)

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Chemistry>Physical Chemistry>Some Basic Concepts of Chemistry>Percentage Composition of Compounds

In Carius method of estimation of halogens,

250 mg

of an organic compound gave

141 mg AgBr

. What is the percentage of bromine in the compound (atomic mass of

Ag = 108

and atomic number of

Br = 80

5 g sample contain only Na2CO3 and Na2SO4 . This sample is dissolved and the volume made up to 250 mL, 25 mL of this solution neutralizes 20 mL of 0.1 M H2SO4 . Calculate the % of Na2SO4 in the sample :

Important Questions on Some Basic Concepts of Chemistry

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5 g sample contain only Na₂CO₃ and Na₂SO₄ . This sample is dissolved and the volume made up to 250 mL, 25 mL of this solution neutralizes 20 mL of 0.1 M H₂SO₄ . Calculate the % of Na₂SO₄ in the sample :