Predict the density of Cs from the density of the following elements: Elements Density Elements Density K 0 . 86 g cm - 3 Ca 1 . 548 g cm - 3 Sc 2 . 991 g cm - 3 Rb 1 . 532 g cm - 3 Sr 2 . 68 g cm - 3 Y 4 . 34 g cm - 3 Cs ? Ba 3 . 51 g cm - 3 La 6 . 16 g cm - 3

The listed elements belong to Group- 1 , 2 and 3 . Consider, the ratio of densities of Ba and Sr of Group- 2 and La and Y of Group- 3 . The ratio of densities of Ba and Sr = 3 . 51 2 . 68 = 1 . 31 and the ratio of densities of La and Y = 6 . 16 4 . 43 = 1 . 42 From the values, we found that the ratio increases by 1 . 42 - 1 . 31 = 0 . 11 . Moving on the same lines, the expected ratio of the densities of Cs and Rb = 1 . 31 - 0 . 11 = 1 . 20 Therefore, Density of Cs Density of Rb = 1 . 20 or density of Cs = Density of Rb × 1 . 20 = 1 . 532 × 1 . 20 = 1 . 84 g cm - 3 The actual density of Cs is 1 . 87 g cm - 3 .

E M B I B E

Pradeep's Chemistry Vol 1>Chapter 3 - Classification of Elements and Periodicity in Properties>TEST YOUR GRIP>Q 13

HARD

11th CBSE

IMPORTANT

Earn 100

Among the halogens, the element having the most negative electron gain enthalpy is .

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Important Questions on Classification of Elements and Periodicity in Properties

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11th CBSE

IMPORTANT

Pradeep's Chemistry Vol 1>Chapter 3 - Classification of Elements and Periodicity in Properties>TEST YOUR GRIP>Q 14

The electronegativity of the elements

C, N, Si

and

P

increases in the order _____.

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11th CBSE

IMPORTANT

Pradeep's Chemistry Vol 1>Chapter 3 - Classification of Elements and Periodicity in Properties>TEST YOUR GRIP>Q 15

An element of Group-

13

which forms a basic oxide is _____.(Boron/Thallium)

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11th CBSE

IMPORTANT

Pradeep's Chemistry Vol 1>Chapter 3 - Classification of Elements and Periodicity in Properties>ADDITIONAL QUESTIONS>Q 1

What was the need for classification of elements?

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11th CBSE

IMPORTANT

Pradeep's Chemistry Vol 1>Chapter 3 - Classification of Elements and Periodicity in Properties>ADDITIONAL QUESTIONS>Q 2

Define Modern Periodic law. Give its theoretical justification.

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11th CBSE

IMPORTANT

Pradeep's Chemistry Vol 1>Chapter 3 - Classification of Elements and Periodicity in Properties>ADDITIONAL QUESTIONS>Q 3

What is the cause of periodicity in properties of the elements? Explain with two examples.

MEDIUM

11th CBSE

IMPORTANT

Pradeep's Chemistry Vol 1>Chapter 3 - Classification of Elements and Periodicity in Properties>ADDITIONAL QUESTIONS>Q 4

Predict the density of $Cs$ from the density of the following elements:

Elements	Density	Elements	Density
$K$	$0.86 g {cm}^{- 3}$	$Ca$	$1.548 g {cm}^{- 3}$
$Sc$	$2.991 g {cm}^{- 3}$	$Rb$	$1.532 g {cm}^{- 3}$
$Sr$	$2.68 g {cm}^{- 3}$	$Y$	$4.34 g {cm}^{- 3}$
$Cs$	?	$Ba$	$3.51 g {cm}^{- 3}$
		$La$	$6.16 g {cm}^{- 3}$