SSC Worksheet for chapter-4 Counting Matter class 9

Worksheet For class 9

Fill in the Blanks

1. Size of an atom is of the range of __________ m.
2. Mass of an atom of Hydrogen is ___________ mass of an atom of carbon.
3. 2 mole of N₂ has ________ moles of nitrogen atom.
4. 2 moles of N₂O₅ has in total _________ moles of atoms of nitrogen and Oxygen.
5. Electronic configuration of Aluminum is 2, 8, 3 and that of chlorine is 2, 8, 7. What is valency of Aluminum and chlorine respectively ? What is the expected molecular formula of the compound of Aluminum and chlorine ?
6. Find molecular mass of Na-23, O-16, P-31, N-14, Al-27, S-32, Cu-63, Br-79
   1. Na₃PO₄
   2. CuBr₂
   3. AlN
   4. (NH₄ )₂ SO₃
7. Percentage of Hydrogen by mass in methane (CH₄) is _______{H – 1, C – 12]
8. Same number of atoms as in 2.5 gms of Hydrogen will weight_____.
9. Number of oxygen atoms which will weight equal to 6.023 -10²³ molecules of CaCo₃ (calcium carbon) are ______.
10. ⊥ mole of Helium gas has _________ atoms of Helium.
11. State law of conservation of matter and low of constant proportion?
12. What do you understand by a molecule and molecular mass?
13. What do you understand by Avogadro number and mole?
14. What do you understand by valency?
15. What is a radical?

Solutions: to worksheet-4 Topic-Counting Matter

1. 10^-10
2. 1/12^th
3. 4
4. 14
5. 3,1 & AlCl₃
6. 1. 164
   2. 221
   3. 41
   4. 148
7. 25%
8. 30 gms
9. 6.25×6.023×10²³ =37.644×10²³
10. 6.02.3×10^-10
11. Consecration Matter: Matter cannot be created nor be dist. By any physical or chemical means. Low of constant proportion or definite proportion .
12. Molecules: Two or more from atoms of elements combine to form molecules. The sum of the atomic masses of the atoms present in a given molecular is the molecules mass of the substance.
13. Avogadro number : A collection of6.022×10²³atoms/molecule or particles is known as Avogadro number represented No.
    Mole : collection of 6.022×10²³atoms or molecules or radicals ions make up a collection to be equal to mole.
14. valeney: cabining of an elements is known as valeney.
15. An atom or group of atoms accepting in electron to form negative charge or lease an electron to form a presiti charge is known as a radical.

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