NCERT solutions for Chemistry - Part 1 and 2 [English] Class 11 chapter 1 - Some Basic Concepts of Chemistry [Latest edition]

Calculate the molar mass of the following:

H₂O

Calculate the molar mass of the following:

CO₂

Calculate the molar mass of the following:

CH₄

Calculate the mass percent of different elements present in sodium sulphate (Na₂SO₄).

Determine the empirical formula of an oxide of iron, which has 69.9% iron and 30.1% dioxygen by mass.

Calculate the amount of carbon dioxide that could be produced when 1 mole of carbon is burnt in air.

Calculate the amount of carbon dioxide that could be produced when 1 mole of carbon is burnt in 16 g of dioxygen.

Calculate the amount of carbon dioxide that could be produced when 2 moles of carbon are burnt in 16 g of dioxygen.

Calculate the mass of sodium acetate (CH₃COONa) required to make 500 mL of 0.375 molar aqueous solution. Molar mass of sodium acetate is 82.0245 g mol^–1.

Calculate the concentration of nitric acid in moles per litre in a sample which has a density, 1.41 g mL^–1and the mass per cent of nitric acid in it being 69%.

How much copper can be obtained from 100 g of copper sulphate (CuSO₄)?

Determine the molecular formula of an oxide of iron in which the mass percent of iron and oxygen are 69.9 and 30.1 respectively. Given that the molar mass of the oxide is 159.69 g mol^–1.

Calculate the atomic mass (average) of chlorine using the following data :-

In three moles of ethane (C₂H₆), calculate the Number of moles of carbon atoms.

In three moles of ethane (C₂H₆), calculate the Number of moles of hydrogen atoms.

In three moles of ethane (C₂H₆), calculate the Number of molecules of ethane.

What is the concentration of sugar (C₁₂H₂₂O₁₁) in mol L^–1 if its 20 g are dissolved in enough water to make a final volume up to 2 L?

If the density of methanol is 0.793 kg L^–1, what is its volume needed for making 2.5 L of its 0.25 M solution?

Pressure is determined as force per unit area of the surface. The SI unit of pressure, Pascal is as shown below:-
1Pa = 1N m^–2
If mass of air at sea level is 1034 g cm^–2, calculate the pressure in Pascal.

What is the SI unit of mass? How is it defined?

Match the following prefixes with their multiples:-

Answer the following question.

Describe what is meant by significant figures.

A sample of drinking water was found to be severely contaminated with chloroform, CHCl₃, supposed to be carcinogenic in nature. The level of contamination was 15 ppm (by mass).

1. Express this in percent by mass.
2. Determine the molality of chloroform in the water sample.

Express the following in the scientific notation: 

0.0048

Express the following in the scientific notation:

234,000

Express the following in the scientific notation:

8008

Express the following in the scientific notation:

500.0

Express the following in the scientific notation:

6.0012

How many significant figures are present in the 0.0025?

How many significant figures are present in the 208?

How many significant figures are present in the 5005?

How many significant figures are present in the 126,000?

How many significant figures are present in the 500.0?

How many significant figures are present in the 2.0034?

Round up the following upto three significant figures:

34.216

Round up the following upto three significant figures:

10.4107

Round up the following upto three significant figures:

0.04597

Round up the following upto three significant figures:

2808

The following data are obtained when dinitrogen and dioxygen react together to form different compounds:-

(a) Which law of chemical combination is obeyed by the above experimental data?Give its statement.

(b) Fill in the blanks in the following conversions:

(i) 1 km = ______ mm = ______ pm

(ii) 1 mg = ______ kg = ______ ng

(iii) 1 mL = ______ L = _______ dm³

If the speed of light is 3.0 ×10⁸ m s^-1, calculate the distance covered by light in 2.00 ns.

In a reaction, \[\ce{A + B2 -> AB2}\]

Identify the limiting reagent, if any, in the following reaction mixture.

300 atoms of A + 200 molecules of B

In a reaction, \[\ce{A + B2 -> AB2}\]

Identify the limiting reagent, if any, in the following reaction mixture.

2 mol A + 3 mol B

In a reaction, \[\ce{A + B2 -> AB2}\]

Identify the limiting reagent, if any, in the following reaction mixture.

2 mol A + 3 mol B

In a reaction, \[\ce{A + B2 -> AB2}\]

Identify the limiting reagent, if any, in the following reaction mixture.

100 atoms of A + 100 molecules of B

In a reaction, \[\ce{A + B2 -> AB2}\]

Identify the limiting reagent, if any, in the following reaction mixture.

5 mol A + 2.5 mol B

In a reaction, \[\ce{A + B2 -> AB2}\]

Identify the limiting reagent, if any, in the following reaction mixture.

2.5 mol A + 5 mol B

Dinitrogen and dihydrogen react with each other to produce ammonia according to the following chemical equation:

\[\ce{N2 (g) + 3H2 (g) → 2NH3 (g)}\]

(i) Calculate the mass of ammonia produced if 2.00 × 10³ g dinitrogen reacts with 1.00 × 10³ g of dihydrogen.

(ii) Will any of the two reactants remain unreacted?

(iii) If yes, which one and what would be its mass?

How are 0.50 mol Na₂CO₃ and 0.50 M Na₂CO₃ different?

If 10 volumes of dihydrogen gas reacts with five volumes of dioxygen gas, how many volumes of water vapour would be produced?

Convert the following into basic units:

28.7 pm

Convert the following into basic units:

15.15 pm

Convert the following into basic units:

25365 mg

Which one of the following will have largest number of atoms?

Calculate the molarity of a solution of ethanol in water in which the mole fraction of ethanol is 0.040 (assume the density of water to be one).

What will be the mass of one ¹²C atom in g?

How many significant figures should be present in the answer of the following calculation:-

`(0.02856 xx 298.15 xx 0.112)/0.5785`

How many significant figures should be present in the answer of the following calculation?

5 × 5.364

How many significant figures should be present in the answer of the following calculation?

0.0125 + 0.7864 + 0.0215

Use the data given in the following table to calculate the molar mass of naturally occurring argon isotopes:-

Calculate the number of atoms of the 52 moles of Ar.

Calculate the number of atoms of the 52 u of He.

Calculate the number of atoms of the 52 g of He.

A welding fuel gas contains carbon and hydrogen only. Burning a small sample of it in oxygen gives 3.38 g carbon dioxide, 0.690 g of water and no other products. A volume of 10.0 L (measured at STP) of this welding gas is found to weigh 11.6 g. Calculate

1. empirical formula,
2. molar mass of the gas, and
3. molecular formula.

Calcium carbonate reacts with aqueous HCl to give CaCl₂ and CO₂ according to the reaction,

\[\ce{CaCO_{3(s)} + 2 HCl_{(aq)} → CaCl_{2(aq)} + CO_{2(g)} + H2O_{(l)}}\]

What mass of CaCO₃ is required to react completely with 25 mL of 0.75 M HCl?

Chlorine is prepared in the laboratory by treating manganese dioxide (MnO₂) with aqueous hydrochloric acid according to the reaction

\[\ce{4HCl_{(aq)} + MnO_{2(s)} → 2H2O_{(l)} + MnCl_{2(aq)} + Cl_{2(g)}}\]

How many grams of HCl react with 5.0 g of manganese dioxide?