Science (English Medium) कक्षा १२ - CBSE Question Bank Solutions

Answer the following question.
Write a chemical reaction to test sulphur dioxide gas. write a chemical equation involved.

Which substance has conductivity in the range 10^-20 to 10^-10 ohm^-1 m^-1?

The property of a substance to offer no resistance to the flow of electricity at a particular temperature is known as ____________.

At what temperature range do most of the metals become superconductors?

Which of the following solids is not an electrical conductor?

1. Mg (s)
2. TiO (s)
3. I₂ (s)
4. H₂O (s)

Graphite is a good conductor of electricity due to the presence of ______.

The van’t Hoff factor (i) accounts for ____________.

Enzymes in the living system ____________.

Enzymes belong to which class of compounds?

We have three aqueous solutions of NaCl labelled as ‘A’, ‘B’ and ‘C’ with concentrations 0.1 M, 0.01 M and 0.001 M, respectively. The value of van’t Hoff factor for these solutions will be in the order ______.

Sulphur trioxide can be obtained by which of the following:

Read the passage given below and answer the following question.

Early crystallographers had trouble solving the structures of inorganic solids using X-ray diffraction because some of the mathematical tools for analyzing the data had not yet been developed. Once a trial structure was proposed, it was relatively easy to calculate the diffraction pattern, but it was difficult to go the other way (from the diffraction pattern to the structure) if nothing was known a priori about the arrangement of atoms in the unit cell. It was important to develop some guidelines for guessing the coordination numbers and bonding geometries of atoms in crystals. The first such rules were proposed by Linus Pauling, who considered how one might pack together oppositely charged spheres of different radii. Pauling proposed from geometric considerations that the quality of the "fit" depended on the radius ratio of the anion and the cation.

If the anion is considered as the packing atom in the crystal, then the smaller cation fills interstitial sites ("holes"). Cations will find arrangements in which they can contact the largest number of anions. If the cation can touch all of its nearest neighbour anions then the fit is good. If the cation is too small for a given site, that coordination number will be unstable and it will prefer a lower coordination structure. The table below gives the ranges of cation/anion radius ratios that give the best fit for a given coordination geometry.

The radius of Ag⁺ ion is 126 pm and of I^- ion is 216 pm. The coordination number of Ag⁺ ion is ______.

Read the passage given below and answer the following question.

Early crystallographers had trouble solving the structures of inorganic solids using X-ray diffraction because some of the mathematical tools for analyzing the data had not yet been developed. Once a trial structure was proposed, it was relatively easy to calculate the diffraction pattern, but it was difficult to go the other way (from the diffraction pattern to the structure) if nothing was known a priori about the arrangement of atoms in the unit cell. It was important to develop some guidelines for guessing the coordination numbers and bonding geometries of atoms in crystals. The first such rules were proposed by Linus Pauling, who considered how one might pack together oppositely charged spheres of different radii. Pauling proposed from geometric considerations that the quality of the "fit" depended on the radius ratio of the anion and the cation.

If the anion is considered as the packing atom in the crystal, then the smaller cation fills interstitial sites ("holes"). Cations will find arrangements in which they can contact the largest number of anions. If the cation can touch all of its nearest neighbour anions then the fit is good. If the cation is too small for a given site, that coordination number will be unstable and it will prefer a lower coordination structure. The table below gives the ranges of cation/anion radius ratios that give the best fit for a given coordination geometry.

A “good fit” is considered to be one where the cation can touch ______.

Read the passage given below and answer the following question.

Early crystallographers had trouble solving the structures of inorganic solids using X-ray diffraction because some of the mathematical tools for analyzing the data had not yet been developed. Once a trial structure was proposed, it was relatively easy to calculate the diffraction pattern, but it was difficult to go the other way (from the diffraction pattern to the structure) if nothing was known a priori about the arrangement of atoms in the unit cell. It was important to develop some guidelines for guessing the coordination numbers and bonding geometries of atoms in crystals. The first such rules were proposed by Linus Pauling, who considered how one might pack together oppositely charged spheres of different radii. Pauling proposed from geometric considerations that the quality of the "fit" depended on the radius ratio of the anion and the cation.

If the anion is considered as the packing atom in the crystal, then the smaller cation fills interstitial sites ("holes"). Cations will find arrangements in which they can contact the largest number of anions. If the cation can touch all of its nearest neighbour anions then the fit is good. If the cation is too small for a given site, that coordination number will be unstable and it will prefer a lower coordination structure. The table below gives the ranges of cation/anion radius ratios that give the best fit for a given coordination geometry.

A solid AB has square planar structure. If the radius of cation A⁺ is 120pm, calculate the maximum possible value of anion B^- ______.

Which of the following oxides shows electrical properties like metals?

The values of Van’t Hoff factors for KCl, NaCl and K₂SO₄, respectively, are ______.

Van’t Hoff factor i is given by the expression:

(i)  i = `"Normal molar mass"/"Abnormal molar mass"`

(ii)  i = `"Abnormal molar mass"/"Normal molar mass"`

(iii) i = `"Observed colligative property"/"Calculated colligative property"`

(iv) i =  `"Calculated colligative property"/"Observed colligative property"`

Which of the following interface cannot be obtained?

Method by which lyophobic sol can be protected?

Which of the following colloids cannot be coagulated easily?

(i) Lyophobic colloids.

(ii) Irreversible colloids.

(iii) Reversible colloids.

(iv) Lyophilic colloids.