Ncert Solutions Chemistry Class 11th
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1.14. What is the S.I. unit of mass? How is it defined?
1.14. What is the S.I. unit of mass? How is it defined?
1.14. S.I. unit of mass is kilogram (kg).
It is defined as the mass of platinum-iridium block stored at international bureau of weights and measures in France.
Upvote 
11.26. (a) Classify following oxides as neutral, acidic, basic or amphoteric:
CO, B2O3, SiO2, CO2, Al2O3, PbO2, Tl2O3
(b) Write suitable equations to show their nature.
11.26. (a) Classify following oxides as neutral, acidic, basic or amphoteric:
CO, B2O3, SiO2, CO2, Al2O3, PbO2, Tl2O3
(b) Write suitable equations to show their nature.
(a) Neutral — CO
Acidic — B2O3, SiO2, CO2
Basic — Tl2O3
Amphoteric — Al2O3, PbO2
(b)-CO does not react with acid as well as base at room temperature.
Being acidic B2O3, SiO2 and CO2 react with alkalis to form salts.
B2O3 + 2NaOH à 2NaBO2 + H2O
SiO2 + NaOH à 2Na2SiO3 + H2O
CO2 + 2NaOH
Upvote 1.13. Pressure is determined as force per unit area of the surface. The S.I. unit of pressure, pascal, is as shown below:
1 Pa = 1 Nm-2.
If mass of air at sea level is 1034 g cm-2, calculate the pressure in pascal.
1.13. Pressure is determined as force per unit area of the surface. The S.I. unit of pressure, pascal, is as shown below:
1 Pa = 1 Nm-2.
If mass of air at sea level is 1034 g cm-2, calculate the pressure in pascal.
1.13. Pressure= Force/Area
But weight = m x g, where m = mass (in kg) and g = 9.8 m/s2
Therefore, Pressure = 1034 g cm-2 x 9.8 m/s2
= 1034 x 10-3 kg x (100 m)2 x 9.8 m/s2
= 101332 Pa
= 1.01332 x 105 Pa
Upvote 1.12. If the density of methanol is 0.793 kg L -1, what is its volume needed for making 2.5 L of its 0.25 M solution?
1.12. If the density of methanol is 0.793 kg L -1, what is its volume needed for making 2.5 L of its 0.25 M solution?
1.12. Density of methanol = 0.793 kg/L, molar mass of methanol (CH3OH) = 32g/mol = 0.032 kg/mol
V1 =? , V2 = 2.5 L, M2 = 0.25 M
We can apply the formula of
M1V1 = M2V2
Or V1 = M2V2/M1
Substituting M1 = density / molar mass, we get
M1 = 0.793/0.032 = 24.78
V1 = 0.25 x 2.5 / 24.78 = 0.02522 L = 25.22 mL
Upvote 1.11. What is the concentration of sugar (C12H22O11) in mol L -1 if its 20 g are dissolved in enough water to make a final volume up to 2 L?
1.11. What is the concentration of sugar (C12H22O11) in mol L -1 if its 20 g are dissolved in enough water to make a final volume up to 2 L?
1.11. Molar mass of sugar = (12 x 12) + (22 x 1) + (11 x 16) =342 g/mol
No. of moles in 352 g of sugar = 1 mol
No. of moles in 20 g = 20 x 1/352 = 0.0585 mol
Therefore, molar concentration = moles of solute / volume of solution in L = 0.0585 / 2 = 0.0293 mol/L
Upvote 11.24. How would you explain the lower atomic radius of Ga as compared to Al?
11.24. How would you explain the lower atomic radius of Ga as compared to Al?
Due to poor shielding effect of d-electrons in Ga, the electrons in gallium experience great force of attraction by nucleus as compared to Al. That is why Ga has lower atomic radius as compared to Al.
Upvote 11.23. Explain why is there a phenomenal decrease in ionization enthalpy from carbon to silicon?
11.23. Explain why is there a phenomenal decrease in ionization enthalpy from carbon to silicon?
Because there is increase in atomic size on moving from carbon to silicon, the screening effect increases. Thus, the force of attraction of nucleus for the valence electron in silicon decreases as compared to carbon. Therefore, the ionization enthalpy decreases from carbon to silicon.
Upvote 11.22. Give reasons:
(i) Conc. HNO3 can be transported in aluminium container.
(ii) A mixture of dilute NaOH and aluminium pieces is used to open drain.
(iii) Graphite is used as lubricant.
(iv) Diamond is used as an abrasive.
(v) Aluminium alloys are used to make aircraft body.
(vi) Aluminium utensils should not be kept in water overnight.
(vii) Aluminium wire is used to make transmission cables.
11.22. Give reasons:
(i) Conc. HNO3 can be transported in aluminium container.
(ii) A mixture of dilute NaOH and aluminium pieces is used to open drain.
(iii) Graphite is used as lubricant.
(iv) Diamond is used as an abrasive.
(v) Aluminium alloys are used to make aircraft body.
(vi) Aluminium utensils should not be kept in water overnight.
(vii) Aluminium wire is used to make transmission cables.
(i) Al reacts with conc. HNO3 to form a very thin film of aluminium oxide on its surface which protects it from further reaction. That is why conc. HNO3 can be transported in aluminium container.
2Al (s) + 6HNO3 (conc.) → Al2O3 (s) + 6NO2 (g) + 3H2O (l)
(ii) NaOH reacts with Al to evolve H2&nbs
Upvote 1.10. In three moles of ethane (C2H6), calculate the following:
(i) Number of moles of carbon atoms
(ii) Number of moles of hydrogen atoms
(iii) Number of molecules of ethane
1.10. In three moles of ethane (C2H6), calculate the following:
(i) Number of moles of carbon atoms
(ii) Number of moles of hydrogen atoms
(iii) Number of molecules of ethane
1.10. (i) 1 mole of C2H6 contains 2 moles of carbon atoms
Therefore, no of moles of C atoms in 3 moles of C2H6 = 6 moles
(ii) 1 mole of C2H6 contains 6 moles of hydrogen atoms
Therefore, no of moles of H atoms in 3 moles of C2H6 =
Upvote 11.21. Explain the following reactions
(a) Silicon is heated with methyl chloride at high temperature in the presence of copper;
(b) Silicon dioxide is treated with hydrogen fluoride;
(c) CO is heated with ZnO;
(d) Hydrated alumina is treated with aqueous NaOH solution.
11.21. Explain the following reactions
(a) Silicon is heated with methyl chloride at high temperature in the presence of copper;
(b) Silicon dioxide is treated with hydrogen fluoride;
(c) CO is heated with ZnO;
(d) Hydrated alumina is treated with aqueous NaOH solution.
(a) Silicon is heated with methyl chloride at high temperature in the presence of copper catalyst at 537 K, methyl substituted chlorosilanes MeSiCl3, Me2→SiCl2→, Me3→SiCl and Me4→Si are formed.
(b) When silicon dioxide is treated with hydrogen fluoride, first SiF4→ is forme
Upvote