Chemistry Class 11 NCERT Solutions: Chapter 1 Some Basic Concepts of Chemistry Part 4

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Q: 10. In three moles of ethane calculate following:

This structure of three moles of ethan C2H6

Structure of Ethane

This structure of three moles of ethan C2H6

(i) Number of moles of carbon atoms

(ii) Number of moles of hydrogen atoms

(iii) Number of molecules of ethane

Answer:

(i) 1 mole of contains moles of carbon atoms.

∴ Number of moles of carbon atoms in moles of

(ii) 1 mole of contains 6 moles of hydrogen atoms.

∴ Number of moles of carbon atoms in moles of

(iii) 1 mole of contains molecules of ethane.

∴ Number of molecules in 3 moles of

Q: 11. What is the concentration of sugar

This structure is disaccharides sucrose example

Structure of Disaccharides (Double Sugars)

This structure is disaccharides sucrose example

In are dissolved in enough water to make a final volume up to ?

Answer:

Molarity (M) of a solution is given by,

∴ Molar concentration of sugar

Image showing Sugar is sucrose, a molecule composed

Image Showing Structure of Concetration of Sugar

Image showing Sugar is sucrose, a molecule composed

Q: 12. If the density of methanol is what is its volume needed for making of its 0.25 M solution?

Image showing methanol structure.

Image Showing Methanol Structure.

Image showing methanol structure.

Answer:

Molar mass of methanol

Molarity of methanol solution

(Since density is mass per unit volume)

Applying,

(Given solution) (Solution to be prepared)