Sign in
12thPass logo
New chatPYQ LibraryDoubtsRank report
Sign in to see Recents

Your guest activity stays on this device

Sign in to save progress →
Sign in

Some Basic Concepts of Chemistry question

2024 · 6 Apr · Shift 1 · Q10
Guest · filters and generic practice availableBrowsing as a guest · PYQ filters and generic practice are available. Sign in only for personalised features and saved progress.
  1. PYQ Library
  2. /JEE Main
  3. /Chemistry
  4. /Some Basic Concepts of Chemistry
  5. /2024 · 6 Apr · Shift 1 · Q10

Some Basic Concepts of Chemistry question

2024 · 6 Apr · Shift 1 · Q10

JEE MainChemistrySome Basic Concepts of ChemistryMCQ+4 / −1
The density of 'xxx' M\mathrm{M}M solution ('xxx' molar) of NaOH\mathrm{NaOH}NaOH is 1.12 g mL−11.12 \mathrm{~g} \mathrm{~mL}^{-1}1.12 g mL−1, while in molality, the concentration of the solution is 3 m3 \mathrm{~m}3 m( 3 molal). Then xxx is (Given : Molar mass of NaOH\mathrm{NaOH}NaOH is 40 g/mol40 \mathrm{~g} / \mathrm{mol}40 g/mol)
  1. A
    3.8
  2. B
    3.0
  3. C
    3.5
  4. D
    2.8
View written solutionFree

Correct answer: B

  1. Given data
  • Density of solution =1.12 g mL−1= 1.12\ \text{g mL}^{-1}=1.12 g mL−1
  • Molality =3 m= 3\ \text{m}=3 m
  • Molar mass of NaOH =40 g mol−1= 40\ \text{g mol}^{-1}=40 g mol−1
  • We need to find molarity xxx.
  1. Use molality definition

Molality means: 3 mol NaOH per 1 kg solvent3\ \text{mol NaOH per } 1\ \text{kg solvent}3 mol NaOH per 1 kg solvent

So, take:

  • mass of solvent =1000 g= 1000\ \text{g}=1000 g
  • moles of NaOH =3= 3=3

Mass of solute: 3×40=120 g3 \times 40 = 120\ \text{g}3×40=120 g

Therefore, total mass of solution: 1000+120=1120 g1000 + 120 = 1120\ \text{g}1000+120=1120 g

  1. Find volume of solution using density

Density is: ρ=massvolume\rho = \frac{\text{mass}}{\text{volume}}ρ=volumemass​

So, volume=11201.12=1000 mL=1 L\text{volume} = \frac{1120}{1.12} = 1000\ \text{mL} = 1\ \text{L}volume=1.121120​=1000 mL=1 L

  1. Now calculate molarity

Molarity === moles of solute per litre of solution.

We have:

  • moles of NaOH =3= 3=3
  • volume of solution =1 L= 1\ \text{L}=1 L

Hence, x=31=3.0x = \frac{3}{1} = 3.0x=13​=3.0

  1. Option check
  • A: 3.83.83.8 ❌
  • B: 3.03.03.0 ✅
  • C: 3.53.53.5 ❌
  • D: 2.82.82.8 ❌

So the correct option is B.

PreviousNext

More from Some Basic Concepts of Chemistry

  • Molality (m) of 3M aqueous solution of NaCl is : (Given : Density of solution =1.25 g mL−1, Molar mass in g mol−1:Na−23,Cl−35.5)2024 · MCQ
  • Combustion of glucose (C6​H12​O6​) produces CO2​ and water. The amount of oxygen (in g) required for the complete combustion of 900 g of glucose is : [Molar mass of glucose…2024 · MCQ
  • A solution is prepared by adding 1 mole ethyl alcohol in 9 mole water. The mass percent of solute in the solution is ​ (Integer answer) (Given : Molar mass in g mol−1 Ethyl alcohol : 46…2024 · Numerical
  • Molality of an aqueous solution of urea is 4.44 m. Mole fraction of urea in solution is x×10−3, Value of x is ​. (Integer answer)2024 · Numerical
  • Molarity (M) of an aqueous solution containing x g of anhyd. CuSO4​ in 500 mL solution at 32∘C is 2×10−1M. Its molality will be ​×10−3 m…2024 · Numerical
  • Mass of methane required to produce 22 g of CO2​ after complete combustion is ​ g. (Given Molar mass in g mol-1 C=12.0, H=1.0, O=16.0)2024 · Numerical
  • The quantity which changes with temperature is :2024 · MCQ
  • 9.3 g of aniline is subjected to reaction with excess of acetic anhydride to prepare acetanilide. The mass of acetanilide produced if the reaction is 100% completed is ​×10−1 g.…2024 · Numerical