Ncert Solutions Chemistry Class 11th
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10 months agoContributor-Level 10
5.16. Radius of the balloon = 10 m
Therefore, volume of the balloon = (4/3)? r3 = (4/3) x (22/7) x (10 m)3
= 4190.5 m3
Volume of He filled at 1.66 bar and 27 °C = 4290.5 m3
To calculate the mass of He,
PV = nRT = (w/M) RT, where M is molar mass of He i.e. 4 g per mole or 4 x 10-3 kg mol-1
=> w = [ (4 x 10-3 kg mol-1) (1.66 bar) (4190.5 m3)] / [ (0.083 bar dm3 K-1 mol-1) (300K)]
= 1117.5 kg
Total mass of the balloon along with He = 100 + 1117.5 = 1217.5 kg
Maximum mass of the air that can be displaced by balloon to go up = volume x density
= 4190.5 m3 x 1.2 kg m-3 = 5028.6 kg
New answer posted
10 months agoContributor-Level 10
5.15. Molar mass of O2 = 32 g/mol
It means, 8 g of O2 has 8/32 mol = 0.25 mol
Molar mass of H2 = 2 g/mol
It means, 4 g of H2 has 4/2 mol = 2 mol
Therefore, total number of moles, n = 2 + 0.25 = 2.25 mol
Given, V = 1dm3, T = 27°C = 300 K, R = 0.083 bar dm3 K-1 mol-1
Applying PV = nRT,
P = nRT / V
= (2.25) (0.083 bar dm3 K-1 mol-1) (300 K) / (1dm3)
= 56.025 bar
New answer posted
10 months agoContributor-Level 10
5.14. Time taken to distribute 1010 wheat grains = 1s
Time taken to distribute Avogadro number of wheat grains = (1s x 6.022 x 1023) / 1010
= 6.022 x 1013 s
= (6.022 x 1013 / 60 x 60 x 24 x 365) year
= 1.9 x 106 years
New answer posted
10 months agoContributor-Level 10
5.13. Molecular mass of N2 = 28g
28 g of N2 has No. of molecules = 6.022 x 1023
1.4 g of N2 has No. of molecules = (6.022 x 1023 x 1.4 g)/28 g= 3.011 x 1022 molecules.
Atomic No. of Nitrogen (N) = 7
1 molecule of N2 has electrons = 7 x 2 = 14
3.011 x 1022 molecules of N2 have electrons= 14 x 3.011 x 1022= 4.215 x1023 electrons.
New answer posted
10 months agoContributor-Level 10
5.12. Given,
P= 3.32 bar
V= 5 dm3
n= 4 mol
R= 0.083 bar dm3 K-1 mol-1
PV = nRT
Or T = PV / nR = 3.32 x 5 dm3 / (4.0 mol x 0.083 bar dm3 K-1 mol-1)
= 50 K
New answer posted
10 months agoContributor-Level 10
9.56. Dihydrogen is prepared from water by the action of alkali metals like Na and K which is a strong reducing agent.
2Na + 2H2O → 2NaOH + H2
2K + 2H2O → 2KOH + H2
New answer posted
10 months agoContributor-Level 10
9.54. Water which does not produce lathers with soap is known as hard water. Hardness is due to the presence of bicarbonates, sulphates and chlorides of Ca2+ and Mg2+.
On boiling, the bicarbonates of calcium and magnesium decompose to insoluble carbonate which can be removed by filtration.
New answer posted
10 months agoContributor-Level 10
9.53. In water molecule, O is SP3 hybridized. Due to stronger lone pair-lone pair repulsion than bond pair-bond pair repulsions, the H-O-H bond angle decreases from 109.5° to 104.5°. Thus, water is bent molecule.
New answer posted
10 months agoContributor-Level 10
9.52. Many transition and inner-transition metals absorb hydrogen into the interstices of their lattices to yield metal like hydrides also called the interstitial hydrides. These hydrides are generally non stoichiometric and their composition vary with temperature and pressure.
For example, TiH1.73, CeH2.7
Two uses of interstitial hydrides are:
(i) In the storage of H2.
(ii) Catalyst for hydrogenation reaction.
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