Class 11 Chemistry Chapter 1 Exercise Questions & Answers (NCERT)
NCERT Class 11 Chemistry Chapter 1 exercise questions with accurate short and numerical answers. QA format, exam-oriented, strictly based on NCERT textbook.
Q1
Calculate the molecular masses of the following substances: (i) H2O (ii) CO2 (iii) CH4
A
(i) H2O = 18 u
(ii) CO2 = 44 u
(iii) CH4 = 16 u
(ii) CO2 = 44 u
(iii) CH4 = 16 u
Q2
Calculate the mass percentage of different elements present in sodium sulphate (Na2SO4).
A
Molar mass of Na2SO4 = 142 g
% Na = 32.4%
% S = 22.5%
% O = 45.1%
% Na = 32.4%
% S = 22.5%
% O = 45.1%
Q3
Determine the empirical formula of an oxide of iron which has 69.9% iron and 30.1% oxygen by mass.
A
Empirical formula = Fe2O3
Q4
Calculate the amount of carbon dioxide produced when (i) 1 mol of carbon is burnt in air (ii) 1 mol of carbon is burnt in 16 g of dioxygen (iii) 2 mol of carbon are burnt in 16 g of dioxygen
A
(i) 44 g CO2
(ii) 22 g CO2
(iii) 22 g CO2
(ii) 22 g CO2
(iii) 22 g CO2
Q5
Calculate the mass of sodium acetate (CH3COONa) required to make 500 mL of 0.375 M solution.
A
Required mass = 15.4 g
Q6
Calculate the concentration of nitric acid in mol L−1 if its density is 1.41 g mL−1 and mass percentage is 69%.
A
Concentration = 15.4 mol L−1
Q7
How much copper can be obtained from 100 g of copper sulphate (CuSO4)?
A
Copper obtained = 39.8 g
Q8
Determine the molecular formula of an oxide of iron whose empirical formula is Fe2O3 and molar mass is 159.8 g mol−1.
A
Molecular formula = Fe2O3
Q9
What is the SI unit of mass?
A
Kilogram (kg)
Q10
What do you mean by significant figures?
A
All the certain digits plus the last uncertain digit in a measured quantity.
Q11
How much copper can be obtained from 100 g of copper sulphate (CuSO4)?
A
Copper obtained = 39.8 g
Q12
Calculate the average atomic mass of chlorine using the following data: Isotope Percentage abundance Cl-35 75.77% Cl-37 24.23%
A
Average atomic mass of chlorine = 35.5 u
Q13
In three moles of ethane (C2H6), calculate: (i) number of moles of carbon atoms (ii) number of moles of hydrogen atoms (iii) number of molecules of ethane
A
Carbon atoms = 6 mol
Hydrogen atoms = 18 mol
Number of molecules = 1.806 × 1024
Hydrogen atoms = 18 mol
Number of molecules = 1.806 × 1024
Q14
Calculate the concentration of sugar (C12H22O11) in mol L−1 if 20 g of sugar is dissolved to make 2 L of solution.
A
Concentration of sugar = 0.029 mol L−1
Q15
If the density of methanol is 0.793 kg L−1, what volume of methanol is required to prepare 2.5 L of 0.25 M solution?
A
Volume of methanol required = 0.025 L
Q16
What is the SI unit of pressure? Calculate the pressure exerted by air at sea level if the mass of air column is 1034 g cm−2.
A
SI unit of pressure = Pascal (Pa)
Pressure exerted by air = 1.01 × 105 Pa
Pressure exerted by air = 1.01 × 105 Pa
Q17
What is the SI unit of mass?
A
Kilogram (kg)
Q18
What is the SI unit of mass?
A
Kilogram (kg)
Q19
What do you mean by significant figures?
A
All the certain digits plus the last uncertain digit present in a measured quantity.
Q20
What is the SI unit of amount of substance?
A
Mole (mol)
Q21
What is the relation between pressure and force?
A
Pressure = Force / Area
Q22
What is the SI unit of force?
A
Newton (N)
Q23
What is the SI unit of length?
A
Metre (m)
Q24
What is the SI unit of temperature?
A
Kelvin (K)
Q25
Define precision in measurement.
A
Precision refers to the closeness of repeated measurements to each other.
Q26
Define accuracy in measurement.
A
Accuracy refers to the closeness of a measured value to the true value.
Q27
State the rules for rounding off significant figures.
A
If the digit to be dropped is less than 5, it is ignored; if it is more than 5, the preceding digit is increased by one.
Q28
How many significant figures are present in 0.004560?
A
4 significant figures
Q29
How many significant figures are present in 2.030?
A
4 significant figures
Q30
How many significant figures are present in 100.0?
A
4 significant figures
Q31
How many significant figures are present in 0.0201?
A
3 significant figures
Q32
What is meant by dimensional analysis?
A
Dimensional analysis is the method of converting one unit into another using conversion factors.
Q33
State the law of definite proportions.
A
A given compound always contains the same elements combined in the same fixed ratio by mass.
Q34
State the law of conservation of mass.
A
Mass is neither created nor destroyed in a chemical reaction.
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