Iodoform test is used to check the presence of carbonyl compounds with the structure R-CO-CH₃ or alcohols with the structure R-CH(OH)-CH₃ in a given unknown substance.

When Iodine and sodium hydroxide are added to a compound that contains either a methyl ketone or a secondary alcohol with a methyl group in the alpha position, a pale yellow precipitate of iodoform or triiodomethane is formed. It can be used to identify aldehydes or ketones. If an aldehyde gives a positive iodoform test, then it must be acetaldehyde since it is the only aldehyde with a CH₃C=O group. Given below are a few example reactions for positive iodoform tests.

Dehydrohalogenation of secondary- and tertiary-alkyl halides involves removal of the ?-hydrogen from the carbon that has the smallest number of hydrogens. This is Saytzeff rule.

According to this rule, major product is the most substituted alkene i.e., major product is obtained by elimination of H from that ?-carbon which has the least number of hydrogen. Product of the reaction in this case is known as Saytzeff product.         

(ii) Hofmann rule : According to this rule, major product is always least substituted alkene i.e., major product is formed from ?-carbon which has maximum number of hydrogen. Product of the reaction in this case is known as Hofmann product.            

Dehydrohalogenation of secondary- and tertiary-alkyl halides involves removal of the ?-hydrogen from the carbon that has the smallest number of hydrogens. This is satzeff rule.

Schottky defect is a type of point defect or imperfection in solids which is caused by a vacant position that is generated in a crystal lattice due to the atoms or ions moving out from the interior to the surface of the crystal.

A Frenkel defect is another form of a point defect which is created when an atom or cation leaves its original place in the lattice structure to create a vacancy while occupying another interstitial position within the solid crystal.

In Schottky defect the difference in size between cation and anion is small. Frenkel defect contains ionic crystals where the anion is larger than the cation. Both anion and cation leave the solid crystal. Usually the smaller ion cation leaves its original lattice structure. Atoms permanently leave the crystal.

Aqueous NaOH or aqueous KOH.

According to the valence bond theory, Electrons in a molecule occupy atomic orbitals rather than molecular orbitals. The atomic orbitals overlap on the bond formation and the larger the overlap the stronger the bond. The metal bonding is essentially covalent in origin and metallic structure involves resonance of electron-pair bonds between each atom and its neighbors.

Calcium chloride is strongly hygroscopic (absorbs water from its surroundings), so it removes moisture from the air, making it dryer. This results in water in the substance to be dried to evaporate into the drier air, and this cycle repeats until the system reaches an equilibrium. Anhydrous calcium chloride is an inorganic salt that easily forms hydrates which promotes its use for removing water from any organic solution.

Sulphur sol and gold sol are Lyophobic sols and are unstable and are build to colloidal size from small particles by the Condensation method by Chemical reactions.

 Oxidation sulphur sol is prepared by passing H₂S into SO₂

1.  H₂S + SO₂ → S (sol) + H₂O 

2. Reduction of AuCl₃ with formaldehyde gives gold sol.

   AuCl₃+ HCHO + 3H₂O → Au (sol) + 3HCOOH + 6HCl

Transition elements (also known as transition metals) are elements that have partially filled d orbitals. IUPAC defines transition elements as an element having a d subshell that is partially filled with electrons, or an element that has the ability to form stable cations with an incompletely filled d orbital.

In general, any element which corresponds to the d-block of the modern periodic table (which consists of groups 3-12) is considered to be a transition element. Even the f-block elements comprising the lanthanides and the actinides can be considered as transition metals.

However, since the f-block elements have incompletely filled f-orbitals, they are often referred to as inner transition elements or inner transition metals. An illustration detailing the position of transition metals on the periodic table along with their general electronic configurations is provided below.

A block of the periodic table is a set of elements unified by the orbitals their valence electrons or vacancies lie in. The term appears to have been first used by Charles Janet. Each block is named after its characteristic orbital: s-block, p-block, d-block, and f-block.

The block names (s, p, d, and f) are derived from the spectroscopic notation for the value of an electron's azimuthal quantum number: shape (0), principal (1), diffuse (2), or fundamental (3). Succeeding notations proceed in alphabetical order, as g, h, etc.

Transition metals share many similar properties including: They can form many compounds with different oxidation states. They can form compounds with different colors. They are metals and conduct electricity. Properties of transition elements include:

• have large charge/radius ratio;
• are hard and have high densities;
• have high melting and boiling points;
• form compounds which are often paramagnetic;
• show variable oxidation states;
• form coloured ions and compounds;
• form compounds with profound catalytic activity;

Subsequently, question is, why do all metals have similar properties? The reason that that elements in the same 'group' have similar chemical properties is because they have the same number of valence electrons. Iron when reacting in chemical reactions loses electrons from its 4s orbital instead of its d orbital.

As discussed earlier, the elements zinc, cadmium, and mercury are not considered transition elements since their electronic configurations are different from other transition metals. However, the rest of the d-block elements are somewhat similar in properties and this similarity can be observed along each specific row of the periodic table. These properties of the transition elements are listed below.

• These elements form coloured compounds and ions. This colour is explained by the d-d transition of electrons.
• There is a relatively low gap in energy between the possible oxidation states of these elements. The transition elements, therefore, exhibit many oxidation states.
• Many paramagnetic compounds are formed by these elements, because of the unpaired electrons in the d orbital.
• A large variety of ligands can bind themselves to these elements. Due to this, a wide variety of stable complexes are formed by transition elements.
• These elements have a large ratio of charge to the radius.
• Transition metals tend to be hard and they have relatively high densities when compared to other elements.
• The boiling points and the melting points of these elements are high, due to the participation of the delocalized d electrons in metallic bonding.
• This metallic bonding of the delocalized d electrons also causes the transition elements to be good conductors of electricity.

Zn, Cd, Hg are not regarded as transition element Because they have the completely filled d-sub-shell with outer electronic configuration (n-1)d¹⁰ns²

Transition elements are those elements in which the atoms or ions (in stable oxidation state) contain partially filled d-orbital. These elements lie in the d-block and show a transition of properties between s-block and p-block. Therefore, these are called transition elements.

Elements such as Zn, Cd, and Hg cannot be classified as transition elements because these have completely filled d-subshell.

Transition metal, any of various chemical elements that have valence electrons—i.e., electrons that can participate in the formation of chemical bonds—in two shells instead of only one. While the term transition has no particular chemical significance, it is a convenient name by which to distinguish the similarity of the atomic structures and resulting properties of the elements so designated. They occupy the middle portions of the long periods of the periodic table of elements between the groups on the left-hand side and the groups on the right. Specifically, they form Groups 3 (IIIb) through 12 (IIb). 

Some of the more well-known transitional metals include titanium, iron, manganese, nickel, copper, cobalt, silver, mercury and gold. Three of the most noteworthy elements are iron, cobalt and nickel as they are only elements known to produce a magnetic field.

Heisenberg’s uncertainty principle states that it is impossible to measure or calculate exactly, both the position and the momentum of an object. This principle is based on the wave-particle duality of matter. Although Heisenberg’s uncertainty principle can be ignored in the macroscopic world (the uncertainties in the position and velocity of objects with relatively large masses are negligible), it holds significant value in the quantum world. Since atoms and subatomic particles have very small masses, any increase in the accuracy of their positions will be accompanied by an increase in the uncertainty associated with their velocities.

In the field of quantum mechanics, Heisenberg’s uncertainty principle is a fundamental theory that explains why it is impossible to measure more than one quantum variables simultaneously. Another implication of the uncertainty principle is that it is impossible to accurately measure the energy of a system in some finite amount of time.