Ncert Solutions Chemistry Class 12th
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New answer posted
6 months agoContributor-Level 10
8.5 The ionization energy increases due to the gradual filling of electrons in the d- subshells. The irregular variation of ionization energy is due to the fact that half-filled and completely filled subshells are more stable and have very high ionization energy.
In case of first ionization energy, Cr ( [Ar]3d54s1) attains the stable configuration (3d5) by losing one electron from s-subshell and hence, it has low ionization energy.
Whereas, Zn has high ionization energy because it has completely filled subshells and are very stable.
Second ionization energies are higher than the first since it becomes difficult to remove an electron
New answer posted
6 months agoContributor-Level 10
5.25
Emulsions –The system which has Liquid as both dispersed phase and dispersion medium. There are two types of emulsions
Oil in Water-Ex-Milk
Water in oil-Ex-Butter.
New answer posted
6 months agoContributor-Level 10
8.4 The E0 (M2+/M) value of a metal depends on the energy changes involved in the following reactions:
1. Sublimation energy: The energy needed to convert one mole of atoms from a solid state to gaseous
2. Ionization energy: The energy supplied to remove electrons from one mole of atoms, which are in the gaseous
3. Hydration energy: The energy emitted to hydrate one mole of
Now, copper has a high ionisation energy and low hydration energy. Hence, the E0 (M2+/M) value for copper is positive.
New answer posted
6 months agoContributor-Level 10
5.23
(i) In this case Tyndall effect is observed i.e. scattering of light by the colloidal particles takes place and the path of light become visible.
(ii) The coagulation takes place in this case positive charge particles of Fe (OH)2 gets attached with Cl-. And of FeCl3 is obtained.
(iii) In this case coagulation will take place. After passing electric current through colloidal solution particle will get attracted towards oppositely charged and lose their charge and coagulate.
New answer posted
6 months agoContributor-Level 10
8.3 Manganese (Z = 25) exhibits the largest number of oxidation states. This is because its electronic configuration is 3d54s2.
Because it has the maximum number of electrons (5 d electrons and 2s electrons) to easily lose and share.
Therefore, it can exhibit an oxidation state of +2 to +7. The compounds are as follows:
Mn (0) as Mn (s), Mn (II) as MnO, Mn (II, III), Mn etc.
New answer posted
6 months agoContributor-Level 10
5.22
Colloidal solutions get classified in 8 Types on the basis of physical state of the dispersed phase and dispersion This are given in following table-
Dispersed phase | Dispersion media | Types of colloids | Example |
Solid | Solid Sol | Gem stone | |
Solid | Liquid | sol | Paints, cell fluid. |
Solid | Gas | Aerosol | Dust, smoke. |
Liquid | Solid | Gel | Butter, Cheese. |
Liquid | Emulsion | Milk, Hair cream. | |
Liquid | Gas | Aerosol | Fog, Mist, Cloud. |
Gas | Solid | Solid Sol | Pumice stone. |
Gas | Liquid | Foam | Froth, soap lather. |
2) Depending upon nature of Particles of dispersed phase it can be classified into 3 categories
Multimolecular Colloids-In this colloidal particle consist of aggregates of atoms having diameter less than
Macromolecular colloids-The colloids in which Large particle aggregates and dissolved into suitable
Associated colloids – This colloids show Colloidal property at higher This contains ions of colloidal size.
3) Depending upon interactions between dispersed phase and dispersion medi
New answer posted
6 months agoContributor-Level 10
8.2 The enthalpy of atomization depends on the strength of the metallic bonding. Stronger the metallic bonding, greater is the enthalpy of atomization. The metallic bonding is strong when there are more unpaired electrons in the atom.
All transition metals (except Zn, electronic configuration: [Kr] 3d10 4s2), have at least one unpaired electron that is responsible for their stronger metallic bonding. Since the Zn atom does not have an unpaired electron, the metallic bonding is weak and hence the enthalpy of atomization is low.
New answer posted
6 months agoContributor-Level 10
5.21
Enzymes are complex nitrogenous organic compounds which are produced by Living plants and animals. They are protein molecules of higher molecular masses. They are effective catalysts termed as “biochemical catalysts”
Mechanism of enzyme catalysis- There are number of cavities present on the surface of colloidal particle of enzymes. They have specific shape and contains group like –COOH, -SH, - OH. etc. they are active centers of enzyme particle molecules of reactant which have complimentary shape fit into this cavities, this forms activated complex Which then decompose to yield products. This reaction occur in 2 steps-
Enzyme (
New answer posted
6 months agoContributor-Level 10
8.1 The elements which have partially filled d or f subshells in any common oxidation state are called as the transition elements. Silver (the Atomic number is 47 and electronic configuration is [Kr] 4d105s1) has a completely filled 4d orbital in its ground state but has two oxidation states (+1, +2).
In the +1 oxidation state, an electron is removed from the s-orbital and in +2 oxidation state, one electron from d-orbital is also removed. Thus, the d-orbital now becomes partially filed (4d9). Hence, it is a transition element.
New answer posted
6 months agoContributor-Level 10
5.20
Multimolecular colloids | Macromolecular colloids |
1) formed by aggregation of large number of atoms of smaller radii. | 1) Formed by particles of large size. |
2) Low molecular masses | 2) High molecular masses. |
3) Weak van there waals forces | 3) Strong van there waals Forces |
4) Ex-sols of gold and sulphur. | 4) Ex-Nylon, starch. |
Associated colloids- They formed by aggregation of large number of ions. instead of atoms or molecules in above two colloids. They have van there waals force directly proportional to concentration of ions. Ex- Soap Sol.
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