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• This method is used to determine the presence of a relative amount of various elements in the plant. 
• In this method when fresh plants are dried at 70 – 80° C in the oven for one or two days so that, all water present in the plant is driven off.
• The remaining part is weighed and the dry weight of the plant is obtained.
• The main constituents of the dry matter are the polysaccharides, lignin, proteins, fats, organic acids and some other elements.
• This dry matter is burnt in a furnace at 600^° C, as a result, all organic compounds are oxidized and are driven off in the form of gases (CO₂ , NH₃ and SO₂).
• The remaining material is called plant ash and contains only mineral elements.
•  The relative amount of various minerals can be determined by analysis of this ash. 
• However, the extent of their utilization and essentiality cannot be determined by this method.

Requirements for Detection of Ash:

(a) Preparation of Ash Extract:

For detection of various elements in plant ash viz., Ca, Mg, Fe, S, P, CI etc. ash material is dissolved in 50% HC1 (v/v) or 50% HNO₃ (v/v) for an hour or more, then filtered through filter paper. Finally selective tests are made for detection of the elements.

(b) Reagents:

1. HCl (50%).

2. HNO₃ (50%).

3. Barium chloride (5%).4. NH₄OH solution (dilute).

5. Ammonium oxalate (saturated).

6. Na₂HPO₄ solution (10%).

7. Potassium ferrocyanide solution (2%).

8. Ammonium thiocyanate solution (5%).

9. Potassium thiocyanate solution (5%).

10. Ammonium molybdate solution (10%).

11. Silver nitrate solution (10%).

12. Disodium hydrogen phosphate solution (10%).

Tests for Detection of Ash:

(a) Tests Using HC1 Extract of Plant Ash:

Experiment:

Test 1:

To about 5-10 ml of filtrate, a few drops of 5% Barium chloride solution is added.

Test 2:

About 20 ml of filtrate is taken in a test tube and made alkaline by addition of a drop of dil. NH₄OH. Finally saturated ammonium oxalate solution is added.

Test 3:

After removal of Calcium oxalate ppt. by filtration, the solution is heated to concentrate and then cooled. Finally 10% disodium hydrogen phosphate solution is added to it.

Test 4 :

To about 10 ml of ash extract 2% pota­ssium ferrocyanide solution is added.

Test 5:

To about 10 ml of extract, 5% ammo­nium thiocyanate or 5% potassium thiocyanate solution is added.

Observations:

A white crystalline precipitate is formed (ppt. of BaSO₄).

A white precipitate of Calcium oxalate is formed.

A white precipitate of ammonium magnesium phosphate is formed.

A dark blue coloration (Prussian blue) is formed.

The solution turns blood red.

Inference:

Presence of sulphur in the ash extract.

Presence of Calcium in the ash extract.

Presence of Magnesium in the ash extract.

Presence of Iron in the ash extract.

Presence of Iron in the ash extract.

(b) Tests using HNO₃ extract of Plant Ash:

Experiment:

Test 6:

To about 10 ml of extract, a few drops of ammonium molybdate soln. added, then heated for 10 min. and cooled.

Test 7:

To a small quantity of extract a few drops of 10% silver nitrate solution are added.

Observation:

A yellowish crystalline precipitate is formed (ppt. of ammonium phosphomolybdate).

A white precipitate is formed.

Inference:

Presence of Phosphorus in the ash extract.

Presence of Chlorine in the ash extract.

He is absorbed in the form of Ferric (Fe³⁺) ion and chlorine are absorbed in the form of Chloride (Cl^-)

Hydroponics: 

The technique of culturing plants in a nutrient solution in place of soil is called liquid culture or hydroponics. This technique is used to determine the requirement of mineral nutrients of plants. 

Vermiculite: 

Vermiculite is a mineral substance found in soil in nature. This is lightweight, chemically inert, heat resistant, the sterile substance having water holding capacity more than soil. This substance is heated in a furnace at 2000°F and the product is used in culturing plants. This technique is called Vermiculoponics.

Nitrogen (N), Phosphorus (P), and Potassium (K)

Plants absorb nitrogen in the form of nitrate and nitrite and as an exception as NH⁴⁺

The answer is (c) B

The answer is (a) Cu, S, Fe, Mn

The answer is (d) 17

The answer is (a) Zn

• Little leaf, or witches' broom, is a disease of sweetpotato caused by a mycoplasma-like organism. 
• Affected plants have small, thickened and sometimes chlorotic young leaves which may be mistaken for zinc deficiency.

The answer is (b) Nitrogen fixation

Nitrogen fixation is a process by which molecular nitrogen in the air is converted into ammonia (NH₃) or related nitrogenous compounds in soil

The answer is (c) Mg

Chlorophylls have a cyclic tetrapyrrole porphyrin head to which a long phytol tail is attached. The cyclic tetrapyrrole has an atom of magnesium coordinated in the centre. The chlorophyll is synthesized from protochlorophyllide on exposure to light. The synthesis of protochlorophyllide requires iron. Hence, the correct answer is the Mg

The answer is (d) Mn, Mo, Cu, Zn

Active Absorption of the mineral is absorbed when the cell sap in plant put large quantities of minerals ion against the concentration gradient like as in a plant the cell sap of the root cells have potassium ions and phosphate ions who is thousand or hundred times greater than in the soil where the plant was growing. It is called active absorption because it require disbursement of metabolic energy. Whereas passive absorption of minerals occurs when the concentration of minerals is higher in the outer solution than the cell sap of the root cells. The minerals absorbed according to the concentration gradient by the simple process of diffusion, this is called passive absorption of minerals because it does not require disbursement of metabolic energy.

Correct option is (c) identify opportunities,

Correct option is (a) controlling

Correct option is (d) All of the above

Correct option is (c) Both a and b

Correct option is (c) Both a and b

Correct option is (d) All of the above

Proof for DNA as the Genetic Material 

▪ Hershey and Chase conducted experiments on bacteriophage to prove that DNA is the genetic material. 

Procedure: 

i. Some bacteriophage virus were grown on a medium that contained radioactive phosphorus (³²P) and some in another medium with radioactive sulphur (³⁵S). 

ii. Viruses grown in the presence of radioactive phosphorus (³²P) contained radioactive DNA.

 iii. Similar viruses grown in presence of radioactive sulphur (³⁵S) contained radioactive protein. 

iv. Both the radioactive virus types were allowed to infect E. coli separately. 

v. Soon after infection, the bacterial cells were gently agitated in blender to remove viral coats from the bacteria. 

vi. The culture was also centrifuged to separate the viral particle from the bacterial cell. 

Observations and Conclusions: 

i. Only radioactive ³²P was found to be associated with the bacterial cell, whereas radioactive ³⁵S was only found in surrounding medium and not in the bacterial cell. 

ii. This indicates that only DNA and not protein coat entered the bacterial cell. 

iii. This proves that DNA is the genetic material which is passed from virus to bacteria and not protein.

Factors responsible for colour of transition metal ions are as follows: 

i. The presence of incompletely filled d-orbitals in metal ions. 

ii. The presence of unpaired electrons in d-orbitals. 

iii. d-d transitions of electrons due to absorption of radiation in the visible region. 

iv. Nature of groups (anions or ligands) linked to the metal ion in the compound or a complex. 

v. Type of hybridisation in metal ion in the complex. 

vi. Geometry of the complex containing transition metal ion.

Note: Colour of 3d transition metal ions:

i. MnO^-₄ ion is intense purple coloured in solution.

ii. The colour is due to charge transfer. An electron is temporarily transferred from O^-2 to Mn⁷⁺ in MnO^-₄.

iii. Due to this, there is a temporary change in the oxidation state of oxygen from -2 to -1 and manganese from +7 to +6.

iv. Charge transfer is possible when the energy levels on the two different atoms involved are appreciably close.

Note: Cr₂O₇^2- , Cr₂O₄^- , MnO₄^- , Cu₂O and Ni-DMG complex are coloured due to charge transfer transitions.

i. The electronic configuration of Cu: [Ar] 3d¹⁰4s¹ and Cu²⁺: [Ar] 3d⁹

ii. In the aqueous solution of copper sulphate, Cu²⁺ forms blue hydrated complex [Cu(H₂O)₆]²⁺ because it has one unpaired electron in 3d subshell. The complex has octahedral geometry.

iii. When CuSO₄ solution is treated with concentrated HCl solution, it forms a new complex [CuCl₄]^2- . [Cu(H₂O)₆]²⁺ + 4Cl^- → [CuCl₄]^2- + 6H₂O

iv. The complex [CuCl₄]^2- has a tetrahedral geometry. Due to the change in geometry and hybridisation of the complex, the colour of the solution changes from blue to yellow.

Correct option is B. Flexi tour

Binomial nomenclature: The binomial nomenclature is made up of two words a generic name and a specific name.

Annelids’ body is bilaterally symmetrical, triploblastic segmented, and has a true body cavity.

Eg: Earthworm, Leech, Nereis.

Correct answer is B.

vgⁿⁱ = Nicked wings

vg^no = Notched wings

vg = Vestigial wings

The transition elements use its (n‐1)d, ns and np orbital and the successive oxidation states differ by unity. For example, Mn shows all the oxidation states from +2 to +7. On other hand non transition elements use its ns, np and nd orbitals and the successive oxidation states differ by two units e.g. Sn²⁺, Sn⁴⁺ etc.

(a) Because Cu⁺ undergoes disproportionation as 2Cu⁺ → Cu + Cu²⁺ Hydiation enthalpy of Cu²⁺ is higher than that of Cu⁺ which Compensates the I.E.₂ of cu involved in the formation of Cu²⁺ ions.

(b)Because of small size of metal, high ionic charge and availability of vacant d-orbital.

Definition : d-block elements are defined as the elements in which the differentiating electron enters d-orbital of the penultimate shell i.e. (n – 1) d-orbital where n is the last shell.

The general electronic configuration can be represented as,

(n – n) d^n-10, ns^n-2

(a) Cr

(b) Cr- 4s¹ 3d⁵
Mn – 4s² 3d⁵ .
Fe – 4s² 3d⁶
Co – 4s² 3d⁷
Ni – 4s² 3d⁸ 

Since there are six unpaired electrons in Cr, it has the maximum paramagnetic behaviour.
(c) Cr²⁺ →3d⁴
Mn²⁺ → 3d⁵
Fe²⁺ → 3d⁶
CO²⁺ → 3d⁷
Ni²⁺ → 3d⁸ 

when two electrons are lost, Mn²⁺ contains maximum number of unpaired electrons ie., Mn²⁺ is the ion with maximum paramagnetic behaviour. Cr²⁺ and Fe²⁺ show similar paramagnetism and so on.

Transition elements are placed in d-block of the modern periodic table.

The transition elements are placed in periods 4 to 7 and groups 3 to 12 of the periodic table.

• d-block elements have electronic configuration,(n – n) d^n-10, ns^l-2.They are all metals.
• In the periodic table, they are placed between the s-block and p-block elements, i.e., in the groups between 2 and 13.
• They show characteristic properties which are intermediate between those of the elements of s-block and p-block.
• Hence, they show a transition in the properties from those of the most electropositive .v-block elements and less
• electropositive (or electronegative) pblock elements.
• Therefore, most of the d-block elements are called transition elements.

In 4d-series maximum number of oxidation states are for Ruthenium Ru (+ 2, + 3, + 4„ + 6, + 7, + 8). In 5d-series, maximum number of oxidation states are for Osmium, Os ( + 2 to + 8).

Any ion that has partially filled d-orbitals is coloured due to d-d transition in visible light. MnO has purpule colour due to charge-transfer. Cu⁺(d¹⁰) and Sc³⁺(d⁰) are white since there is no d-d transition.

Similarity :

• They are placed between .s-block and p-block of the periodic table.
• All elements are metals showing metallic characters.
• Some are paramagnetic.
• Most of them give coloured compounds.
• They have catalytic properties.
• They form complexes.
• They have variable oxidation states.

Differences :

• In 4d and 5d series lanthanide and actinoid contraction is observed. In 3d series atomic size changes are less marked.
• 4d and 5d elements have high coordination numbers compared to 3d elements.
• 4d and 5d series have similar properties whereas 3d series have different properties.

Due to diagonal relationship, since their atomic size, electro negativity and ionisation potential are almost the same.

Noble gases being monoatomic have no inter atomic forces except weak dispersion forces. Hence they have low boiling points.

Xe⁺ [PtF₆]^- . Neil Bartlett,observed the reaction of a noble gas. First, he prepared a red compound which is formulated as O₂ + [PtF₆] ^-. He, then realised that the first ionization enthalpy of molecular oxygen (1175 kJmol^–1) was almost identical with that of xenon (1170 kJ mol^–1). He made efforts to prepare same type of compound with Xe and was successful in preparing another red colour compound Xe⁺ [PtF₆] ^- by mixing PtF₆ and xenon. 

An element whose differentiating electron is a 4d-electron will be present in fifth period of the periodic table.

Due to diagonal relationship, since their atomic size, electronegativity and ionization potential are almost the same.

Fifth period of the periodic table consist of elements in which the differentiating electron is a 4d electron.

The condition for something to be called as matter is that it should occupy space and have mass.

These metals have maximum number of unpaired electrons in their (n-1) d orbitals.

i. All the transition elements are metallic in nature. They either have hexagonal close pack (hcp), cubic close pack (ccp) or body centred cubic lattices which is a characteristic of true metal. 

ii. They are hard, lustrous, malleable and ductile with high melting and boiling points, and having good thermal and electrical conductivities. 

iii. Low ionization enthalpies and presence of vacant orbitals in the outermost shell results in metallic character due to formation of metallic bonds. 

iv. In addition to the electrons from outermost energy level, the unpaired d-electrons also contribute for the bond formation. So, greater the number of unpaired d-electrons, stronger is the bonding. This is due to the formation of covalent bonds by the overlapping of the d-orbitals containing unpaired electrons.

Mn element is the highest number of oxidation states.

Cd²⁺ ion has no unpaired electron. 

The elements in which the last electron enters the d-orbital of the penultimate shell i.e.,(n-1)d-orbital where ‘n’ is the outermost shell, are called d-block elements

Their general valence or outer electronic configuration is (n - 1)d^1-10 ns^1-2.

Transition elements have partly filled d sub shell in its ground state or any of its oxidation.

Group 12 elements are not considered as transition elements due to completely filled d- orbital in ground state as well as oxidation states.