Numerical problems based on mole concept 9th
Chemistry
1. Calculate the number
of moles of magnesium present in a magnesium ribbon weighing 12 g. Molar atomic
mass of magnesium is 24g/ mol
2. Verify by calculating
that

(a) 5 moles of CO^{2} and 5 moles of H_{2}O do not
have the same mass.

(b) 240 g of calcium and
240 g magnesium elements have a mole ratio of 3:5.

3. Find the ratio by mass of the combining elements
in the following compounds.

(a) CaCO_{3} (b) MgCl_{2} (c) H2SO4 (d) C2H_{5}OH (e) NH_{3} (f) Ca(OH)_{2}

4. Calcium chloride when dissolved in water
dissociates into its ions according to the following equation. CaCl_{2} (aq) → Ca_{2}+ (aq) + 2Cl– (aq)

Calculate the number of
ions obtained from CaCl_{2} when
222 g of it is dissolved in water.

5. The difference in the mass of 100 moles each of
sodium atoms and sodium ions is 5.48002 g. Compute the mass of an electron.

6. Cinnabar (HgS) is a prominent ore of mercury. How
many grams of mercury are present in 225 g of pure HgS? Molar mass of Hg and S
are 200.6 g /mol and 32 g/ mol respectively.

7. The mass of one steel screw is 4.11g. Find the
mass of one mole of these steel screws. Compare this value with the mass of the
Earth (5.98 × 10^{24}kg). Which one of the two is heavier and by how
many times?

8. A sample of vitamin C is known to contain 2.58
×10^{24} oxygen atoms.
How many moles of oxygen atoms are present in the sample?

9. Compute the difference
in masses of 103 moles each of magnesium atoms and magnesium ions. (Mass of an
electron = 9.1×10^{–31} kg)

10. Compute the number of
ions present in 5.85 g of sodium chloride.

11. A gold sample contains 90% of gold and the rest
copper. How many atoms of gold are present in one gram of this sample of gold?

12. Compute the
difference in masses of one mole each of aluminium atoms and one mole of its
ions. (Mass of an electron is 9.1×10^{–28} g). Which one is heavier?

13. A silver ornament of mass ‘m’ gram is polished
with gold equivalent to 1% of the mass of silver. Compute the ratio of the
number of atoms of gold and silver in the ornament.

14. A sample of ethane (C2H6) gas has the same mass
as 1.5 ×10^{20} molecules
of methane (CH_{4}). How many C_{2}H_{6} molecules does the sample of gas
contain?

15. Fill in the blanks

(a) In a chemical
reaction, the sum of the masses of the reactants and products remains
unchanged. This is called ————.

(b) A group of atoms
carrying a fixed charge on them is called ————.

(c) The formula unit mass
of Ca_{3} (PO_{4})_{2} is ————.

(d) Formula of sodium
carbonate is ———— and that of ammonium sulphate is ——

Download solved paper bsed on mole concept

9th Mole concept numerical problems solved-CBSE SET- 1

## 13 comments:

please give the answers....!

it would be more helpful...

answers should be there to check is the ans right or wrongm

Do you have an answer key .like if you have got please post it so that it would be more helpful.

pleaseadanswerkey

bekkar

bekkar

ans kha he

mai hindi boltha he

im sorry were is the answers

Solutions of the question should be given to clear the doubts

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It's not useful without answers. Answers should be given, otherwise it will become the worst site!!!!!

Yah bro...

Its bekkar

👍👍👍

not soo bad but ok.....

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