5 moles of A B 2 weigh 125 × 10 - 3 k g and 10 moles of A 2 B 2 weigh 300 × 10 - 3 k g . The molar mass of A ( M A ) and molar mass of B ( M B ) in k g m o l - 1 are:

M A = 5 × 10 - 3 and M B = 10 × 10 - 3

M A = 25 × 10 - 3 and M B = 50 × 10 - 3

M A = 50 × 10 - 3 and M B = 25 × 10 - 3

M A = 10 × 10 - 3 and M B = 5 × 10 - 3

If Avogadro number N A , is changed from 6.022 × 10 23 m o l - 1 to 6.022 × 10 20 m o l - 1 , this would change:

The definition of mass in units of grams

The ratio of chemical species to each other in a balanced equation.

The ratio of elements to each other in a compound.

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To determine the exact amount of acetic acid in a sample, $1.5 g$ of the sample is titrated against $0.5 N$ solution of $KOH$ . For the titration, $30 mL$ solution of $KOH$ is required. The percentage content (weight wise) of acetic acid in the given sample is

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Important Questions on Some Basic Concepts of Chemistry

EASY

Chemistry>Physical Chemistry>Some Basic Concepts of Chemistry>Percentage Composition, Empirical Formula and Molecular Formula

An amount of

18 g

glucose corresponds to:

EASY

Chemistry>Physical Chemistry>Some Basic Concepts of Chemistry>Percentage Composition, Empirical Formula and Molecular Formula

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, Empirical Formula and Molecular Formula

Mass % of carbon in ethanol is

EASY

Chemistry>Physical Chemistry>Some Basic Concepts of Chemistry>Percentage Composition, Empirical Formula and Molecular Formula

The ratio of masses of oxygen and nitrogen in a particular gaseous mixture is 1 : 4. The ratio of number of their molecules is:

MEDIUM

Chemistry>Physical Chemistry>Some Basic Concepts of Chemistry>Percentage Composition, Empirical Formula and Molecular Formula

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)

EASY

Chemistry>Physical Chemistry>Some Basic Concepts of Chemistry>Percentage Composition, Empirical Formula and Molecular Formula

The amount of oxygen in

3.6

moles of water is:

EASY

Chemistry>Physical Chemistry>Some Basic Concepts of Chemistry>Percentage Composition, Empirical Formula and Molecular Formula

The volume of oxygen at STP required to burn 2.4 g of carbon completely is:

EASY

Chemistry>Physical Chemistry>Some Basic Concepts of Chemistry>Percentage Composition, Empirical Formula and Molecular Formula

The percentage composition of carbon by mole in methane is:

MEDIUM

Chemistry>Physical Chemistry>Some Basic Concepts of Chemistry>Percentage Composition, Empirical Formula and Molecular Formula

A mixture of gases contains

H_{2}

and

O_{2}

gases in the ratio of

1 : 4

(w/w). What is the molar ratio of the two gases in the mixture?

EASY

Chemistry>Physical Chemistry>Some Basic Concepts of Chemistry>Percentage Composition, Empirical Formula and Molecular Formula

Suppose the elements

X

and

Y

combine to form two compounds

X Y_{2}

and

X_{3} Y_{2}

. When

0.1 mole

X Y_{2}

weighs

10 g

and

0.05 mole

X_{3} Y_{2}

weighs

9 g

, the atomic weights of

X

and

Y

are

HARD

Chemistry>Physical Chemistry>Some Basic Concepts of Chemistry>Percentage Composition, Empirical Formula and Molecular Formula

The ratio of mass percent of

C and H

of an organic compound

(C_{X} H_{Y} O_{Z})

6 : 1 .

If one molecule of the above compound

(C_{X} H_{Y} O_{Z})

contains half as much oxygen as required to burn one molecule of compound

C_{X} H_{Y}

completely to

{CO}_{2}

and

H_{2} O .

The empirical formula of the compound

C_{X} H_{Y} O_{Z}

EASY

Chemistry>Physical Chemistry>Some Basic Concepts of Chemistry>Percentage Composition, Empirical Formula and Molecular Formula

The number of water molecules is maximum in

HARD

Chemistry>Physical Chemistry>Some Basic Concepts of Chemistry>Percentage Composition, Empirical Formula and Molecular Formula

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, Empirical Formula and Molecular Formula

A compound has the following composition by weight;

N a = 18.60 %, S = 25.80 %, H = 4.02 %

and

O = 51.58 %

Assuming that all the hydrogen atoms in the compound are part of water of crystallization, the correct molecular formula of the compound is

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Chemistry>Physical Chemistry>Some Basic Concepts of Chemistry>Percentage Composition, Empirical Formula and Molecular Formula

Ferrous sulphate heptahydrate is used to fortify foods with iron. The amount (in grams) of the salt required to achieve

10 p p m

of iron in

100 k g

of wheat is ____________. (Up to two decimal place)
Atomic weight:

F e = 55.85; S = 32.00; O = 16.00

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Chemistry>Physical Chemistry>Some Basic Concepts of Chemistry>Percentage Composition, Empirical Formula and Molecular Formula

The flocculation value of

H C l

for arsenic sulphide

s o l

30 m m o l L^{- 1}

. If

H_{2} S O_{4}

is used for the flocculation of arsenic sulphide, the amount, in grams, of

H_{2} S O_{4}

250 m l

required for the above purpose is ________. (Round off to two digits after decimal.)
(molecular mass of

H_{2} {S O}_{4} = 98 g / m o l

EASY

Chemistry>Physical Chemistry>Some Basic Concepts of Chemistry>Percentage Composition, Empirical Formula and Molecular Formula

5

moles of

A B_{2}

weigh

125 \times 10^{- 3} k g

and

10

moles of

A_{2} B_{2}

weigh

300 \times 10^{- 3} k g

. The molar mass of A

(M_{A})

and molar mass of

B (M_{B})

k g {m o l}^{- 1}

are:

MEDIUM

Chemistry>Physical Chemistry>Some Basic Concepts of Chemistry>Percentage Composition, Empirical Formula and Molecular Formula

An unknown chlorohydrocarbon has 3.55 % of chlorine. If each molecule of the hydrocarbon has one chlorine atom only; chlorine atoms present in 1 g of chlorohydrocarbon are :(Atomic wt. of

Cl = 35 .5 u;

Avogadro constant

= 6 .023 \times 10^{23} {mol}^{- 1}

)

EASY

Chemistry>Physical Chemistry>Some Basic Concepts of Chemistry>Percentage Composition, Empirical Formula and Molecular Formula

If Avogadro number

N_{A}

, is changed from

6.022 \times 10^{23} m o l^{- 1}

6.022 \times 10^{20} m o l^{- 1}

, this would change:

HARD

Chemistry>Physical Chemistry>Some Basic Concepts of Chemistry>Percentage Composition, Empirical Formula and Molecular Formula

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

To determine the exact amount of acetic acid in a sample, 1.5g of the sample is titrated against 0.5N solution of KOH. For the titration, 30mL solution of KOH is required. The percentage content (weight wise) of acetic acid in the given sample is

Important Questions on Some Basic Concepts of Chemistry

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To determine the exact amount of acetic acid in a sample, $1.5 g$ of the sample is titrated against $0.5 N$ solution of $KOH$ . For the titration, $30 mL$ solution of $KOH$ is required. The percentage content (weight wise) of acetic acid in the given sample is