Chemistry · Textbook solutions

Some Basic Concepts of Chemistry

Every solved example, exercise, and miscellaneous question — in the order the textbook teaches them. · 53 questions

1. Some Basic Concepts of Chemistry — worked examples

7 q

Solved Examples

Worked · 7
  1. Solved Ex.1.1
    Mass of an atom of oxygen in gram is 26.56896×10−2426.56896 \times 10^{-24} g. What is the atomic mass of oxygen in u ?
  2. Solved Ex.1.2
    Calculate the average atomic mass of neon using the following data :
    IsotopeAtomic massNatural Abundance
    20Ne^{20}\mathrm{Ne}19.9924 u90.92%
    21Ne^{21}\mathrm{Ne}20.9940 u0.26 %
    22Ne^{22}\mathrm{Ne}21.9914 u8.82 %
  3. Solved Ex.1.3
    Find the mass of 1 molecule of oxygen (O2)(\mathrm{O_2}) in amu (u) and in grams.
  4. Solved Ex.1.4
    Find the formula mass of i. NaCl\mathrm{NaCl} ii. Cu(NO3)2\mathrm{Cu(NO_3)_2}
  5. Solved Ex.1.5
    Calculate the number of moles and molecules of urea present in 5.6 g of urea.
  6. Solved Ex.1.6
    Calculate the number of atoms in each of the following i. 52 moles of Argon (Ar) ii. 52 u of Helium (He) iii. 52 g of Helium (He)
  7. Solved Ex.1.7
    Calculate the number of moles and molecules of ammonia (NH3)(\mathrm{NH_3}) gas in a volume 67.2 dm3\mathrm{dm^3} of it measured at STP.

Exercises

46 q

Choose the most correct option

Practice · 9
  1. Choose the most correct option.
    Ex Q.1 (A)
    A sample of pure water, whatever the source always contains ______ by mass of oxygen and 11.1 % by mass of hydrogen.
    1. A.
      88.9
    2. B.
      18
    3. C.
      80
    4. D.
      16
  2. Ex Q.1 (B)
    Which of the following compounds can NOT demonstrate the law of multiple proportions ?
    1. A.
      NO, NO2\mathrm{NO},\ \mathrm{NO_2}
    2. B.
      CO, CO2\mathrm{CO},\ \mathrm{CO_2}
    3. C.
      H2O, H2O2\mathrm{H_2O},\ \mathrm{H_2O_2}
    4. D.
      Na2S, NaF\mathrm{Na_2S},\ \mathrm{NaF}
  3. Ex Q.1 (C)
    Which of the following temperature will read the same value on Celsius and Fahrenheit scales.
    1. A.
      −40∘-40^\circ
    2. B.
      +40∘+40^\circ
    3. C.
      −80∘-80^\circ
    4. D.
      −20∘-20^\circ
  4. Ex Q.1 (D)
    SI unit of the quantity electric current is ______
    1. A.
      Volt
    2. B.
      Ampere
    3. C.
      Candela
    4. D.
      Newton
  5. Ex Q.1 (E)
    In the reaction N2+3H2⟶2NH3\mathrm{N_2} + 3\mathrm{H_2} \longrightarrow 2\mathrm{NH_3}, the ratio by volume of N2\mathrm{N_2}, H2\mathrm{H_2} and NH3\mathrm{NH_3} is 1 : 3 : 2 This illustrates the law of
    1. A.
      definite proportion
    2. B.
      reciprocal proportion
    3. C.
      multiple proportion
    4. D.
      gaseous volumes
  6. Ex Q.1 (F)
    Which of the following has maximum number of molecules ?
    1. A.
      7 g N2\mathrm{N_2}
    2. B.
      2 g H2\mathrm{H_2}
    3. C.
      8 g O2\mathrm{O_2}
    4. D.
      20 g NO2\mathrm{NO_2}
  7. Ex Q.1 (G)
    How many g of H2O\mathrm{H_2O} are present in 0.25 mol of it ?
    1. A.
      4.5
    2. B.
      18
    3. C.
      0.25
    4. D.
      5.4
  8. Ex Q.1 (H)
    The number of molecules in 22.4 cm3\mathrm{cm^3} of nitrogen gas at STP is
    1. A.
      6.022×10206.022 \times 10^{20}
    2. B.
      6.022×10236.022 \times 10^{23}
    3. C.
      22.4×102022.4 \times 10^{20}
    4. D.
      22.4×102322.4 \times 10^{23}
  9. Ex Q.1 (I)
    Which of the following has the largest number of atoms ?
    1. A.
      1 g Au (s)
    2. B.
      1 g Na (s)
    3. C.
      1 g Li (s)
    4. D.
      1 g Cl2\mathrm{Cl_2} (g)

Answer the following questions

Practice · 9
  1. Answer the following questions.
    Ex Q.2 (A)
    State and explain Avogadro's law.
  2. Ex Q.2 (B)
    Point out the difference between 12 g of carbon and 12 u of carbon
  3. Ex Q.2 (C)
    How many grams does an atom of hydrogen weigh ?
  4. Ex Q.2 (D)
    Calculate the molecular mass of the following in u. a. NH3\mathrm{NH_3} b. CH3COOH\mathrm{CH_3COOH} c. C2H5OH\mathrm{C_2H_5OH}
  5. Ex Q.2 (E)
    How many particles are present in 1 mole of a substance ?
  6. Ex Q.2 (F)
    What is the SI unit of amount of a substance ?
  7. Ex Q.2 (G)
    What is meant by molar volume of a gas ?
  8. Ex Q.2 (H)
    State and explain the law of conservation of mass.
  9. Ex Q.2 (I)
    State the law of multiple proportions.

Give one example of each

Practice · 4
  1. Give one example of each
    Ex Q.3 (A)
    homogeneous mixture
  2. Ex Q.3 (B)
    heterogeneous mixture
  3. Ex Q.3 (C)
    element
  4. Ex Q.3 (D)
    compound

Solve problems

Practice · 18
  1. Solve problems :
    Ex Q.4 (A)
    What is the ratio of molecules in 1 mole of NH3\mathrm{NH_3} and 1 mole of HNO3\mathrm{HNO_3}.
  2. Ex Q.4 (B)
    Calculate number of moles of hydrogen in 0.448 litre of hydrogen gas at STP
  3. Ex Q.4 (C)
    The mass of an atom of hydrogen is 1.008 u. What is the mass of 18 atoms of hydrogen.
  4. Ex Q.4 (D)
    Calculate the number of atom in each of the following (Given : Atomic mass of I = 127 u). a. 254 u of iodine (I) b. 254 g of iodine (I)
  5. Ex Q.4 (E)
    A student used a carbon pencil to write his homework. The mass of this was found to be 5 mg. With the help of this calculate. a. The number of moles of carbon in his homework writing. b. The number of carbon atoms in 12 mg of his homework writting
  6. Ex Q.4 (F)
    Arjun purchased 250 g of glucose (C6H12O6)(\mathrm{C_6H_{12}O_6}) for Rs 40. Find the cost of glucose per mole.
  7. Ex Q.4 (G)
    The natural isotopic abundance of 10B^{10}\mathrm{B} is 19.60% and 11B^{11}\mathrm{B} is 80.40 %. The exact isotopic masses are 10.13 and 11.009 respectively. Calculate the average atomic mass of boron
  8. Ex Q.4 (H)
    Convert the following degree Celsius temperature to degree Fahrenheit. a. 40 ∘C40\ ^\circ\mathrm{C} b. 30 ∘C30\ ^\circ\mathrm{C}
  9. Ex Q.4 (I)
    Calculate the number of moles and molecules of acetic acid present in 22 g of it.
  10. Ex Q.4 (J)
    24 g of carbon reacts with some oxygen to make 88 grams of carbon dioxide. Find out how much oxygen must have been used.
  11. Ex Q.4 (K)
    Calculate number of atoms is each of the following. (Average atomic mass : N = 14 u, S = 32 u) a. 0.4 mole of nitrogen b. 1.6 g of sulfur
  12. Ex Q.4 (L)
    2.0 g of a metal burnt in oxygen gave 3.2 g of its oxide. 1.42 g of the same metal heated in steam gave 2.27 of its oxide. Which law is verified by these data ?
  13. Ex Q.4 (M)
    In two moles of acetaldehyde (CH3CHO)(\mathrm{CH_3CHO}) calculate the following a. Number of moles of carbon b. Number of moles of hydrogen c. Number of moles of oxygen d. Number of molecules of acetaldehyde
  14. Ex Q.4 (N)
    Calculate the number of moles of magnesium oxide, MgO in i. 80 g and ii. 10 g of the compound. (Average atomic masses of Mg = 24 and O = 16)
  15. Ex Q.4 (O)
    What is volume of carbon dioxide, CO2\mathrm{CO_2} occupying by i. 5 moles and ii. 0.5 mole of CO2\mathrm{CO_2} gas measured at STP.
  16. Ex Q.4 (P)
    Calculate the mass of potassium chlorate required to liberate 6.72 dm3\mathrm{dm^3} of oxygen at STP. Molar mass of KClO3\mathrm{KClO_3} is 122.5 g mol−1\mathrm{g\ mol^{-1}}.
  17. Ex Q.4 (Q)
    Calculate the number of atoms of hydrogen present in 5.6 g of urea, (NH2)2CO(\mathrm{NH_2})_2\mathrm{CO}. Also calculate the number of atoms of N, C and O.
  18. Ex Q.4 (R)
    Calculate the mass of sulfur dioxide produced by burning 16 g of sulfur in excess of oxygen in contact process. (Average atomic mass : S = 32 u, O = 16 u)

Explain

Practice · 6
  1. Explain
    Ex Q.5 (A)
    The need of the term average atomic mass.
  2. Ex Q.5 (B)
    Molar mass.
  3. Ex Q.5 (C)
    Mole concept.
  4. Ex Q.5 (D)
    Formula mass with an example.
  5. Ex Q.5 (E)
    Molar volume of gas.
  6. Ex Q.5 (F)
    Types of matter (on the basis of chemical composition).