Class 9 Science CBSE worksheet for Atoms and Molecules

Given below are the Class 9 Science CBSE worksheet for Atoms and Molecules
a) Short questions
b) True and False problems
c) Fill in the blank's
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Fill In The Blanks:-

  1. During a chemical reaction, the sum of the _________ of the reactants and products remain unchanged.
  2. In a pure chemical compound, elements are always present in a ________ proportion by mass.
  3. Clusters of atoms that act as an ion are called __________ ions.
  4. In ionic compounds, the charge on each ion is used to determine the ________of tye compound.
  5. The Avogadro constant _________ is defined as the umber of atoms in exactly ________ of crbon-12
  6. Mass of 1 mole of a substance is called its __________.
  7. The abbreviation used for length names of elements are termed as their _______.
  8. A chemical formula is also known as a ________.
  9. Those ions which are formed from single atoms are called _________.
  10. Ionic compounds are formed by the combination between ________ an ______.
  11. The valency of an ion is _________ to the charge on the ion.
  12. Mole is a link between the __________ and __________.
  13. The SI unit of amount of a substance is __________.

True / False:

  1. Formula mass of Na2O is 62 amu.
  2. Those particles which have more or less electrons than the normal atoms are called ions.
  3. Formula for sulphur dioxide is SO3.
  4. Molar mass of ethyne (C2H2) is 26 g/mol.
  5. 22 gm of CO2 consists of 1 mole.
  6. Number of molecules in 32 gram of oxygen is 6.02 x 1023.
  7. Water is an atom.
  8. Formula for sulphur dioxide is SO2.
  9. Clusters of atoms that act as an ion is called lopyatomic ion.
  10. Mass of 1 mole of a substance is called its formula mass.
  11. In a pure chemical compound, elements are always present in a definite proportion by mass.

Very Short Answer Questions:

  1. Define term mole.
  2. What is Avogadro’s umber?
  3. What is gram atomic weight?
  4. What is the difference between CO2 and 2CO2?
  5. Name the following compounds PC3 and SO2.
  6. In the smallest whole-number ratio must N and O atoms combine to make dinitrogen to tetroxide N2O4? What is the mole ratio of the elements I this compound?
  7. How many moles of sodium atoms correspond to 1.56 x 1021 atoms of sodium?
  8. What is the relationship between the formula weight of a substance and its molar mass?
  9. How many grams of silver are in 0.263 mol of g?
  10. How many atoms are 1.00 x 10-9 g of lead?
  11. How many grams of iron are needed to combine with 25.6g of O to make Fe2O3?
  12. What is the mass of 4 moles of aluminum atoms? ( Atomic mass of AI = 27u)
  13. Calculate the mass of 6.022 x 1022 atoms of He.
  14. Calculate the number of moles in 3.011 x 1022 molecules of carbon dioxide.
  15. A samp0le of 45.8g of H2SO4 contains how many moles of H2O4?
  16. What s the mass in grams of 5 moles of Fe?
  17. How many moles of NaCI are present in 20 gm of the substance?
  18. How many grams of O is present in 50 gm of CaCO3?
  19. How many grams of CO2 are present in 0.1 mole CO2?
  20. Describe the difference between the mass of a mole of oxygen atoms (O) and the mass of a mole of oxygen molecules (O2).
  21. What do you understand by the term Formula unit?


Fill in the blanks:

  1. Masses
  2. Definite
  3. Polyatomic
  4. Chemical formula
  5. 86.022 x 1023, 12g
  6. Molar mass
  7. Symbol
  8. Molecular formula
  9. Simple ins
  10. Metal and non- metals
  11. Equal
  12. Mass of atoms & number of atoms
  13. Mole

True / False:

  1. True
  2. True
  3. False
  4. True
  5. False
  6. True
  7. False
  8. True
  9. True
  10. False
  11. True


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