3:Uncertainty in measurement Class 11 Notes | EduRev

Class 11 : 3:Uncertainty in measurement Class 11 Notes | EduRev

 Page 1


CBSE TEST PAPER-03 
CLASS - XI CHEMISTRY (Basic Concepts of Chemistry) 
Topic: - Uncertainty in measurement 
Marks: 20 
1. What is the difference between precision and accuracy? [1] 
2. What do you understand by significant figures? [1] 
3. How many significant figures are present in [3] 
(a) 4.01 × 10
2
(b) 8.256 
(c) 100 
4. State law of definite proportions. [1] 
5. Explain law of multiple proportions with an example. [2] 
6. State Avogadro’s law. [1] 
7. Write Postulates of Dalton’s atomic theory. [2] 
8. Define one atomic mass unit (amu). [1] 
9. Calculate molecular mass of – [2] 
C 2H 6, C 12H 22O 11, H 2SO 4, H 3PO 4 
10. What is formula mass? [1] 
7
Page 2


CBSE TEST PAPER-03 
CLASS - XI CHEMISTRY (Basic Concepts of Chemistry) 
Topic: - Uncertainty in measurement 
Marks: 20 
1. What is the difference between precision and accuracy? [1] 
2. What do you understand by significant figures? [1] 
3. How many significant figures are present in [3] 
(a) 4.01 × 10
2
(b) 8.256 
(c) 100 
4. State law of definite proportions. [1] 
5. Explain law of multiple proportions with an example. [2] 
6. State Avogadro’s law. [1] 
7. Write Postulates of Dalton’s atomic theory. [2] 
8. Define one atomic mass unit (amu). [1] 
9. Calculate molecular mass of – [2] 
C 2H 6, C 12H 22O 11, H 2SO 4, H 3PO 4 
10. What is formula mass? [1] 
7
CBSE TEST PAPER-03 
CLASS - XI CHEMISTRY   [ANSWERS] 
Topic: - Uncertainty in measurement 
Ans1: Precision means the closeness of various measurements for the same quantity. 
Accuracy is the agreement of a particular value to the true value of the result.  
Ans2: Significant figures are meaningful digits which are known with certainty. The 
uncertainty in experimental or the calculated value is indicated by mentioning the 
number of significant figures.  
Ans3: (a) 4.01 × 10
2
 – Three
(b) 8.256 – Four  
(c) 100 – One 
Ans4: Law of definite proportions states that a given compound always contains exactly 
the same proportion of elements by weight.  
Ans5: The law of multiple proportions rays that if two elements can 
combine to form more than one compound, the masses of one 
element that combine with a fixed mass of other element are 
in a ratio of small whole numbers. e.g. hydrogen and oxygen 
can combine to form water as well as hydrogen peroxide.  
Here, the masses of oxygen (16g & 32g) which combine with a fixed mass of 
hydrogen (2g) bear a simple ratio i.e., 16:32 = 1:2.  
Ans6: According to Avogadro’s law, equal volumes of gases at the same temperature and 
pressure should contain equal number of molecules.   
Ans7  Postulates of Dalton’s atomic theory – 
8
Page 3


CBSE TEST PAPER-03 
CLASS - XI CHEMISTRY (Basic Concepts of Chemistry) 
Topic: - Uncertainty in measurement 
Marks: 20 
1. What is the difference between precision and accuracy? [1] 
2. What do you understand by significant figures? [1] 
3. How many significant figures are present in [3] 
(a) 4.01 × 10
2
(b) 8.256 
(c) 100 
4. State law of definite proportions. [1] 
5. Explain law of multiple proportions with an example. [2] 
6. State Avogadro’s law. [1] 
7. Write Postulates of Dalton’s atomic theory. [2] 
8. Define one atomic mass unit (amu). [1] 
9. Calculate molecular mass of – [2] 
C 2H 6, C 12H 22O 11, H 2SO 4, H 3PO 4 
10. What is formula mass? [1] 
7
CBSE TEST PAPER-03 
CLASS - XI CHEMISTRY   [ANSWERS] 
Topic: - Uncertainty in measurement 
Ans1: Precision means the closeness of various measurements for the same quantity. 
Accuracy is the agreement of a particular value to the true value of the result.  
Ans2: Significant figures are meaningful digits which are known with certainty. The 
uncertainty in experimental or the calculated value is indicated by mentioning the 
number of significant figures.  
Ans3: (a) 4.01 × 10
2
 – Three
(b) 8.256 – Four  
(c) 100 – One 
Ans4: Law of definite proportions states that a given compound always contains exactly 
the same proportion of elements by weight.  
Ans5: The law of multiple proportions rays that if two elements can 
combine to form more than one compound, the masses of one 
element that combine with a fixed mass of other element are 
in a ratio of small whole numbers. e.g. hydrogen and oxygen 
can combine to form water as well as hydrogen peroxide.  
Here, the masses of oxygen (16g & 32g) which combine with a fixed mass of 
hydrogen (2g) bear a simple ratio i.e., 16:32 = 1:2.  
Ans6: According to Avogadro’s law, equal volumes of gases at the same temperature and 
pressure should contain equal number of molecules.   
Ans7  Postulates of Dalton’s atomic theory – 
8
1. Matter consists of indivisible atoms.
2. All the atoms of a given element have identical properties including atomic mass.
Atoms of different element differ in mass. 
3. Compounds are formed when atoms of different elements combine in a fixed ratio.
4. Chemical reaction involves reorganization of atoms. These are neither created nor
destroyed 
Ans8: One atomic mass unit (amu) is defined as a mass exactly equal to one – twelfth the 
mass of one carbon – 12 atom.  
Ans9: 
2 6
(2 12) (6 1) 30 C H = × + × =
12 22 11
2 4
3 4
(12 12) (22 1) (11 16) 342
(2 1) 32 (4 16) 98
(1 3) 31 (4 16) 98
C H O
H SO
H PO
= × + × + × =
= × + + × =
= × + + × =
Ans10:  When a substance does not contain discrete molecules as their constituent units and 
have a three dimensional structure, formula mass is used to calculate molecular 
mass which is sum of all the atomic masses of atom present in the formula.  
9
Read More
Offer running on EduRev: Apply code STAYHOME200 to get INR 200 off on our premium plan EduRev Infinity!

Related Searches

study material

,

3:Uncertainty in measurement Class 11 Notes | EduRev

,

pdf

,

Summary

,

Previous Year Questions with Solutions

,

Semester Notes

,

Sample Paper

,

3:Uncertainty in measurement Class 11 Notes | EduRev

,

Extra Questions

,

Important questions

,

shortcuts and tricks

,

Viva Questions

,

past year papers

,

video lectures

,

MCQs

,

Free

,

Objective type Questions

,

mock tests for examination

,

ppt

,

3:Uncertainty in measurement Class 11 Notes | EduRev

,

Exam

,

practice quizzes

;