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

Two students performed the same experiment separately and each one of them recorded two readings of mass which are given below. Correct reading of mass is 3.0 g. On the basis of given data, mark the correct option out of the following statements.

A measured temperature on Fahrenheit scale is 200 °F. What will this reading be on Celsius scale?

What will be the molarity of a solution, which contains 5.85 g of NaCl(s) per 500 mL?

If 500 mL of a 5 M solution is diluted to 1500 mL, what will be the molarity of the solution obtained?

The number of atoms present in one mole of an element is equal to Avogadro number. Which of the following element contains the greatest number of atoms?

If the concentration of glucose \[\ce{(C6H12O6)}\] in blood is 0.9 g L^–1, what will be the molarity of glucose in blood?

What will be the molality of the solution containing 18.25 g of \[\ce{HCl}\] gas in 500 g of water?

One mole of any substance contains 6.022 × 10²³ atoms/molecules. Number of molecules of \[\ce{H2SO4}\] present in 100 mL of 0.02 M \[\ce{H2SO4}\] solution is ______.

What is the mass percent of carbon in carbon dioxide?

The empirical formula and molecular mass of a compound are \[\ce{CH2O}\] and 180 g respectively. What will be the molecular formula of the compound?

If the density of a solution is 3.12 g mL^–1, the mass of 1.5 mL solution in significant figures is ______.

Which of the following statements about a compound is incorrect?

Which of the following statements is correct about the reaction given below:

\[\ce{4Fe(s) + 3O2(g) -> 2Fe2O3(g)}\]

Which of the following reactions is not correct according to the law of conservation of mass.

Which of the following statements indicates that law of multiple proportion is being followed?

One mole of oxygen gas at STP is equal to :

(i) 6.022 × 10²³ molecules of oxygen

(ii) 6.022 × 10²³ atoms of oxygen

(iii) 16 g of oxygen

(iv) 32 g of oxygen

Sulphuric acid reacts with sodium hydroxide as follows:

\[\ce{H2SO4 + 2NaOH -> Na2SO4 + 2H2O}\]

When 1 L of 0.1 M sulphuric acid solution is allowed to react with 1 L of 0.1 M sodium hydroxide solution, the amount of sodium sulphate formed and its molarity in the solution obtained is:

(i) 0.1 mol L^–1

(ii) 7.10 g

(iii) 0.025 mol L^–1

(iv) 3.55 g

Which of the following pairs have the same number of atoms?

(i) \[\ce{16 g of O2 (g) and 4 g of H2(g)}\]

(ii) \[\ce{16 g of O2 and 44 g of CO2}\]

(iii) \[\ce{28 g of N2 and 32 g of O2}\]

(iv) \[\ce{12 g of C(s) and 23 g of Na(s)}\]

Which of the following solutions have the same concentration?

(i) \[\ce{20 g of NaOH in 200 mL of solution}\]

(ii) \[\ce{0.5 mol of KCl in 200 mL of solution}\]

(iii) \[\ce{40 g of NaOH in 100 mL of solution}\]

(iv) \[\ce{20 g of KOH in 200 mL of solution}\]

16 g of oxygen has same number of molecules as in:

(i) \[\ce{16 g of CO}\]

(ii) \[\ce{28 g of N2}\]

(iii) \[\ce{14 g of N2}\]

(iv) \[\ce{1.0 g of H2}\]

Which of the following terms are unitless?

(i) Molality

(ii) Molarity

(iii) Mole fraction

(iv) Mass percent

One of the statements of Dalton’s atomic theory is given below: “Compounds are formed when atoms of different elements combine in a fixed ratio”

Which of the following laws is not related to this statement?

(i) Law of conservation of mass

(ii) Law of definite proportions

(iii) Law of multiple proportions

(iv) Avogadro law

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

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

`(2.5 xx 1.25 xx 3.5)/2.01`

What is the symbol for \[\ce{SI}\] unit of mole? How is the mole defined?

What is the difference between molality and molarity?

Calculate the mass percent of calcium, phosphorus and oxygen in calcium phosphate \[\ce{Ca3(PO4)2}\].

45.4 L of dinitrogen reacted with 22.7 L of dioxygen and 45.4 L of nitrous oxide was formed. The reaction is given below:

\[\ce{2N2(g) + O2(g) -> 2N2O(g)}\]

Which law is being obeyed in this experiment? Write the statement of the law?

If two elements can combine to form more than one compound, the masses of one element that combine with a fixed mass of the other element, are in whole number ratio.

Is this statement true?

If two elements can combine to form more than one compound, the masses of one element that combine with a fixed mass of the other element, are in whole number ratio.

If yes, according to which law?

If two elements can combine to form more than one compound, the masses of one element that combine with a fixed mass of the other element, are in whole number ratio.

Give one example related to this law.

Calculate the average atomic mass of hydrogen using the following data:

Hydrogen gas is prepared in the laboratory by reacting dilute \[\ce{HCl}\] with granulated zinc. Following reaction takes place.

\[\ce{Zn + 2HCl -> ZnCl2 + H2}\]

Calculate the volume of hydrogen gas liberated at STP when 32.65 g of zinc reacts with \[\ce{HCl}\]. 1 mol of a gas occupies 22.7 L volume at STP; atomic mass of \[\ce{Zn}\] = 65.3 u.

The density of 3 molal solution of \[\ce{NaOH}\] is 1.110 g mL^–1. Calculate the molarity of the solution.

Volume of a solution changes with change in temperature, then, will the molality of the solution be affected by temperature? Give reason for your answer.

If 4 g of \[\ce{NaOH}\] dissolves in 36 g of \[\ce{H2O}\], calculate the mole fraction of each component in the solution. Also, determine the molarity of solution (specific gravity of solution is 1g mL^–1).

The reactant which is entirely consumed in reaction is known as limiting reagent. In the reaction \[\ce{2A + 4B -> 3C + 4D}\], when 5 moles of A react with 6 moles of B, then which is the limiting reagent?

The reactant which is entirely consumed in reaction is known as limiting reagent. In the reaction \[\ce{2A + 4B -> 3C + 4D}\], when 5 moles of A react with 6 moles of B, then calculate the amount of C formed? 

Match the following:

Match the following physical quantities with units

Assertion (A): The empirical mass of ethene is half of its molecular mass.

Reason (R): The empirical formula represents the simplest whole number ratio of various atoms present in a compound.

Assertion (A): One atomic mass unit is defined as one-twelfth of the mass of one carbon-12 atom.

Reason (R): Carbon-12 isotope is the most abundunt isotope of carbon and has been chosen as standard.

Assertion (A): Significant figures for 0.200 is 3 where as for 200 it is 1.

Reason (R): Zero at the end or right of a number are significant provided they are not on the right side of the decimal point.

Assertion (A): Combustion of 16 g of methane gives 18 g of water.

Reason (R): In the combustion of methane, water is one of the products.

A vessel contains 1.6 g of dioxygen at STP (273.15K, 1 atm pressure). The gas is now transferred to another vessel at constant temperature, where pressure becomes half of the original pressure. Calculate volume of the new vessel.

A vessel contains 1.6 g of dioxygen at STP (273.15K, 1 atm pressure). The gas is now transferred to another vessel at constant temperature, where pressure becomes half of the original pressure. Calculate number of molecules of dioxygen.

Calcium carbonate reacts with aqueous \[\ce{HCl}\] to give \[\ce{CaCl2}\] and \[\ce{CO2}\] according to the reaction given below:

\[\ce{CaCO3(s) + 2HCl (aq) -> CaCl2 (aq) + CO2(g) + H2O (l)}\]

What mass of \[\ce{CaCl2}\] will be formed when 250 mL of 0.76 M \[\ce{HCl}\] reacts with 1000 g of \[\ce{CaCO3}\]? Name the limiting reagent. Calculate the number of moles of \[\ce{CaCl2}\] formed in the reaction.

Define the law of multiple proportions. Explain it with two examples. How does this law point to the existence of atoms?

A box contains some identical red coloured balls, labelled as A, each weighing 2 grams. Another box contains identical blue coloured balls, labelled as B, each weighing 5 grams. Consider the combinations AB, AB₂, A₂B and A₂B₃ and show that law of multiple proportions is applicable.