The number of valence electrons of an element that is involved in chemical reactions is called the valency of that element. Valency of an element is the measure of combining capacity with other atoms when it forms a chemical compound or molecule.

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The formula of calcium oxide is $CaO$ .

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Important Questions on Atoms and Molecules

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Science>Chemistry>Atoms and Molecules>Writing Chemical Formulae

The formulae of an oxide of an element

M

MO

. The formulae of its phosphate is

MEDIUM

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If the vapour density of the carbon containing gaseous substance is

13

, which of the following is its molecular formula?

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Science>Chemistry>Atoms and Molecules>Writing Chemical Formulae

An element X with atomic number

13

combines with another element Y of atomic number

17

. The formula of the compound formed and the nature of the bond will be:

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Science>Chemistry>Atoms and Molecules>Writing Chemical Formulae

The element ‘X’ has an electronic configuration

2, 8, 3 .

Element ‘Y’ has an electronic configuration

2, 8 7

. The chemical formula of the compound formed when they react is

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Science>Chemistry>Atoms and Molecules>Writing Chemical Formulae

An organic compound contains

60 % C; 4.48 % H

and

35.5 % O .

Its empirical formula is

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Science>Chemistry>Atoms and Molecules>Writing Chemical Formulae

Write chemical formula of Magnesium Chloride.

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Science>Chemistry>Atoms and Molecules>Writing Chemical Formulae

The molecular formula of chloride of a metal M is

{MCl}_{2}

. The molecular formula of an oxide of M will be:

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Science>Chemistry>Atoms and Molecules>Writing Chemical Formulae

An element ‘P’ which belongs to

13 th

group of the periodic table and another element ‘Q’ belongs to

16 th

group. The formula of the compound formed if they react with each other is:

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Science>Chemistry>Atoms and Molecules>Writing Chemical Formulae

Molecular formula of a compound is

C_{6} H_{18} O_{3}

. Find its empirical formula.

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Science>Chemistry>Atoms and Molecules>Writing Chemical Formulae

Find the empirical formula and the molecular formula of an organic compound from the data given below:

$C = 75.92 %, H = 6.32 % and N = 17.76 %$

The vapour density of the compound is $39.5$ . $[C = 12, H = 1, N = 14]$

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A solution of a substance 'X' is used for whitewashing.

(a) Name the substance 'X' and write its formula.

(b) Write the reaction of the substance with water.

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Science>Chemistry>Atoms and Molecules>Writing Chemical Formulae

The empirical formula and molecular mass of a compound are

{CH}_{2} O

and

180 g

respectively. The molecular formula of the compound will be

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Science>Chemistry>Atoms and Molecules>Writing Chemical Formulae

In a compound

C, H

and

N

are present in

9 : 1 : 3.5

by weight. If molecular weight of compound is

108

, the molecular formula of compound is

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Science>Chemistry>Atoms and Molecules>Writing Chemical Formulae

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}

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Science>Chemistry>Atoms and Molecules>Writing Chemical Formulae

{Na}_{2} {CO}_{3}

is:

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Science>Chemistry>Atoms and Molecules>Writing Chemical Formulae

What is the chemical formula for the compound hydrogen chloride?

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Science>Chemistry>Atoms and Molecules>Writing Chemical Formulae

The formula of a compound formed by

{Ca}^{2 +}

and

O^{2 -}

is:

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Science>Chemistry>Atoms and Molecules>Writing Chemical Formulae

Define valency.

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The chemical formula of the copper nitrate is _____.

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What is the chemical formula for the compound Aluminium oxide ?

The formula of calcium oxide is CaO.

Important Questions on Atoms and Molecules

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The formula of calcium oxide is $CaO$ .