Some Basic Concepts of Chemistry
- 6.02 × 1020 molecules of urea are present in 100 ml of its solution. Jee Answer: B) 0.01 M Moles of urea: n = frac6.02×10²⁰6.02×10²³ = 1×10⁻³\ mol Volume of solution = 100\ mL = 0.1\ L . Molarity = frac10⁻³\ mol0.... 1
- Number of atoms in 558.5 gram Fe (at. wt. of Fe = 55.85 g mol-1) is Answer: (a) twice that in 60 g carbon Moles of Fe = 558.5/55.85 = 10 mol, so the number of atoms is 10N_A = 6.023×10²⁴ . Check each option:... 1
- In a compound C, H and N atoms are present in 9 : 1 : 3.5 by weight . Answer: C₆H₈N₂ Divide each mass by the atomic mass to get the mole ratio: C: 9/12 = 0.75 H: 1/1 = 1 N: 3.5/14 = 0.25 Dividing by the smalles... 1
- With increase of temperature, which of these changes? JEE Option C is correct molarity Temperature has no effect on mass but it has significant effect on volumes. Hence molality, mole fraction, mass... 1
- If both FeX2 & FeY3 are found to exist, X & Y can be : (1) X = F, Cl, Br, I Y = F, Cl, Br (2) X = Cl, Br, (1) X = F, Cl, Br, I :: Y = F, Cl, Br is the correct option Explaination:: FeI₃ does not exist as I^(–) reduces Fe³⁺ to Fe²⁺. 2Fe³⁺ + 2I – →... 1