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Classification of Elements and Periodicity in Properties
Calculate the molecular mass of the following: (i) H2O (ii) CO2 (ii...

Use the periodic table to answer the fol | Class 11 Chemistry Chapter Classification of Elements and Periodicity in Properties, Classification of Elements and Periodicity in Properties NCERT Solutions

Question:

Calculate the molecular mass of the following:
(i) H₂O
(ii) CO₂
(iii) CH₄

Answer:

Molecules are made up of atoms & are quite small, therefore the actual mass of a molecule cannot be detrmined.It is expressed as the relative mass.C-12 isotope is used to express the relative molecular masses of substances.Thus molecular mass of a substance may be defined as: the average relative mass of its molecule as compared to the mass of carbon atom taken as 12 amu.

(i) H₂O:

The molecular mass of water, H₂O

= (2 × Atomic mass of hydrogen) + (1 × Atomic mass of oxygen)

= [2(1.0084) + 1(16.00 u)]

= 2.016 u + 16.00 u

= 18.016

= 18.02 u

(ii) CO₂:

The molecular mass of carbon dioxide, CO₂

= (1 × Atomic mass of carbon) + (2 × Atomic mass of oxygen)

= [1(12.011 u) + 2 (16.00 u)]

= 12.011 u + 32.00 u

= 44.01 u

(iii) CH₄:

The molecular mass of methane, CH₄

= (1 × Atomic mass of carbon) + (4 × Atomic mass of hydrogen)

= [1(12.011 u) + 4 (1.008 u)]

= 12.011 u + 4.032 u

= 16.043 u

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Comments

aman
2019-03-10 09:42:55

iodine is a non metal

Anirudh
2019-03-07 07:25:35

Iodine must have been bored by being in non metals, so it went metals, I think so.......

Jashan
2018-09-23 12:41:06

Chlorine and flourine have 7 electrons in their outermost shell not 5

Kittu
2018-09-09 10:52:44

Iodine is not a metal sir it's a non-metal

neha kumari
2018-09-02 23:15:17

4 no ka Hg answer nhi hoga kya

Sandip
2017-10-22 19:49:32

Identify non-metal from the following a. F b. Co C.fe d. Na

Shaitan singh
2017-10-10 11:02:32

Bromine is liquid.

rahul
2017-09-01 18:55:48

iodine is a non metal

kushala
2015-10-03 04:47:26

Tq it helps me a lot!!!!

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Welcome to the NCERT Solutions for Class 11 Chemistry - Chapter . This page offers a step-by-step solution to the specific question from Excercise 1 , Question 27: Use the periodic table to answer the following questions. (a) Identify an element with five electro....

Use the periodic table to answer the fol | Class 11 Chemistry Chapter Classification of Elements and Periodicity in Properties, Classification of Elements and Periodicity in Properties NCERT Solutions

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