The incorrect postulates of the Dalton's atomic theory are : (A) Atoms of different elements differ in mass. (B) Matter consists of divisible atoms. (C) Compounds are formed when atoms of different element combine in a fixed ratio. (D) All the atoms of given element have different properties including mass. (E) Chemical reactions involve reorganisation of atoms. Choose the correct answer from the options given below :

The transition metal having highest $3^{\text{rd }}$ ionisation enthalpy is :

Given below are two statements : Statement (I) : Both metals and non-metals exist in p and d-block elements. Statement (II) : Non-metals have higher ionisation enthalpy and higher electronegativity than the metals. In the light of the above statements, choose the most appropriate answer from the options given below :

Given below are two statements : Statement (I) : The $$4\mathrm{f}$$ and $$5\mathrm{f}$$ - series of elements are placed separately in the Periodic table to preserve the principle of classification. Statement (II) : S-block elements can be found in pure form in nature. In the light of the above statements, choose the most appropriate answer from the options given below :

Consider the following elements. Which of the following is/are true about $${\mathrm{A}}^{\prime },{\mathrm{B}}^{\prime },{\mathrm{C}}^{\prime }$$ and $${\mathrm{D}}^{\prime }$$ ? A. Order of atomic radii: $${\mathrm{B}}^{\prime }<{\mathrm{A}}^{\prime }<{\mathrm{D}}^{\prime }<{\mathrm{C}}^{\prime }$$ B. Order of metallic character: $${\mathrm{B}}^{\prime }<{\mathrm{A}}^{\prime }<{\mathrm{D}}^{\prime }<{\mathrm{C}}^{\prime }$$ C. Size of the element: $${\mathrm{D}}^{\prime }<{\mathrm{C}}^{\prime }<{\mathrm{B}}^{\prime }<{\mathrm{A}}^{\prime }$$ D. Order of ionic radii: $${\mathrm{B}}^{\prime +}<{\mathrm{A}}^{1^{+}}<{\mathrm{D}}^{\prime +}<{\mathrm{C}}^{+}$$ Choose the correct answer from the options given below :

The correct sequence of electron gain enthalpy of the elements listed below is A. Ar B. Br C. F D. S Choose the most appropriate from the options given below:

Given below are two statements : one is labelled as Assertion $$\mathbf{A}$$ and the other is labelled as Reason $$\mathbf{R}$$ : Assertion A : The first ionisation enthalpy decreases across a period. Reason $$\mathbf{R}$$ : The increasing nuclear charge outweighs the shielding across the period. In the light of the above statements, choose the most appropriate from the options given below :

Given below are two statements : Statement I : The electronegativity of group 14 elements from $$\mathrm{Si}$$ to $$\mathrm{Pb}$$, gradually decreases. Statement II : Group 14 contains non-metallic, metallic, as well as metalloid elements. In the light of the above statements, choose the most appropriate from the options given below :

Given below are two statements: Statement I : Fluorine has most negative electron gain enthalpy in its group. Statement II : Oxygen has least negative electron gain enthalpy in its group. In the light of the above statements, choose the most appropriate from the options given below

The element having the highest first ionization enthalpy is

Anomalous behavior of oxygen is due to its

Given below are two statements: One is labelled as Assertion A and the other is labelled as Reason R: Assertion A: $${\mathrm{H}}_2\mathrm{Te}$$ is more acidic than $${\mathrm{H}}_2\mathrm{S}$$. Reason R: Bond dissociation enthalpy of $${\mathrm{H}}_2\mathrm{Te}$$ is lower than $${\mathrm{H}}_2\mathrm{S}$$. In the light of the above statements, choose the most appropriate from the options given below:

Given below are two statements: Statement - I: Along the period, the chemical reactivity of the elements gradually increases from group 1 to group 18 . Statement - II: The nature of oxides formed by group 1 elements is basic while that of group 17 elements is acidic. In the light of the above statements, choose the most appropriate from the options given below:

Match List I with List II. .tg {border-collapse:collapse;border-spacing:0;} .tg td{border-color:black;border-style:solid;border-width:1px;font-family:Arial, sans-serif;font-size:14px; overflow:hidden;padding:10px 5px;word-break:normal;} .tg th{border-color:black;border-style:solid;border-width:1px;font-family:Arial, sans-serif;font-size:14px; font-weight:normal;overflow:hidden;padding:10px 5px;word-break:normal;} .tg .tg-baqh{text-align:center;vertical-align:top} .tg .tg-amwm{font-weight:bold;text-align:center;vertical-align:top} .tg .tg-0lax{text-align:left;vertical-align:top} List I Species List II Electronic distribution (A) $$\mathrm{C}{\mathrm{r}}^{+2}$$ (I) $$3{\mathrm{d}}^8$$ (B) $$\mathrm{M}{\mathrm{n}}^{+}$$ (II) $$3{\mathrm{d}}^{3}4{\mathrm{s}}^1$$ (C) $$\mathrm{N}{\mathrm{i}}^{+2}$$ (III) $$3{\mathrm{d}}^4$$ (D) $${\mathrm{V}}^{+}$$ (IV) $$3{\mathrm{d}}^{5}4{\mathrm{s}}^1$$ Choose the correct answer from the options given below :

Match List I with List II .tg {border-collapse:collapse;border-spacing:0;} .tg td{border-color:black;border-style:solid;border-width:1px;font-family:Arial, sans-serif;font-size:14px; overflow:hidden;padding:10px 5px;word-break:normal;} .tg th{border-color:black;border-style:solid;border-width:1px;font-family:Arial, sans-serif;font-size:14px; font-weight:normal;overflow:hidden;padding:10px 5px;word-break:normal;} .tg .tg-baqh{text-align:center;vertical-align:top} .tg .tg-amwm{font-weight:bold;text-align:center;vertical-align:top} .tg .tg-0lax{text-align:left;vertical-align:top} LIST I (Element) LIST II (Electronic Configuration) A. $$\mathrm{N}$$ I. $$[\mathrm{Ar}]3{\mathrm{d}}^{10}4{\mathrm{s}}^{2}4{\mathrm{p}}^5$$ B. $$\mathrm{S}$$ II. $$[\mathrm{Ne}]3{\mathrm{s}}^{2}3{\mathrm{p}}^4$$ C. $$\mathrm{Br}$$ III. $$[\mathrm{He}]2{\mathrm{s}}^{2}2{\mathrm{p}}^3$$ D. $$\mathrm{Kr}$$ IV. $$[\mathrm{Ar}]3{\mathrm{d}}^{10}4{\mathrm{s}}^{2}4{\mathrm{p}}^6$$ Choose the correct answer from the options given below:

Match List I with List II .tg {border-collapse:collapse;border-spacing:0;} .tg td{border-color:black;border-style:solid;border-width:1px;font-family:Arial, sans-serif;font-size:14px; overflow:hidden;padding:10px 5px;word-break:normal;} .tg th{border-color:black;border-style:solid;border-width:1px;font-family:Arial, sans-serif;font-size:14px; font-weight:normal;overflow:hidden;padding:10px 5px;word-break:normal;} .tg .tg-c3ow{border-color:inherit;text-align:center;vertical-align:top} .tg .tg-7btt{border-color:inherit;font-weight:bold;text-align:center;vertical-align:top} .tg .tg-0pky{border-color:inherit;text-align:left;vertical-align:top} LIST I LIST II A. Melting Point $$[\mathrm{K}]$$ I. $$\mathrm{T}1>\mathrm{In}>\mathrm{Ga}>\mathrm{A}1>\mathrm{B}$$ B. Ionic Radius $$[{\mathrm{M}}^{+3}/\mathrm{pm}]$$ II. $$\mathrm{B}>\mathrm{T}1>\mathrm{Al}\approx \mathrm{Ga}>\mathrm{In}$$ C. $${\Delta }_{\mathrm{i}}{\mathrm{H}}_1[\mathrm{kJ}{\mathrm{mol}}^{-1}]$$ III. $$\mathrm{T}1>\mathrm{In}>\mathrm{Al}>\mathrm{Ga}>\mathrm{B}$$ D. Atomic Radius [pm] IV. $$\mathrm{B}>\mathrm{A}1>\mathrm{T}1>\mathrm{In}>\mathrm{Ga}$$ Choose the correct answer from the options given below:

Given below are two statements : Statement (I) : The oxidation state of an element in a particular compound is the charge acquired by its atom on the basis of electron gain enthalpy consideration from other atoms in the molecule. Statement (II) : $$\mathrm{p}\pi -\mathrm{p}\pi$$ bond formation is more prevalent in second period elements over other periods. In the light of the above statements, choose the most appropriate answer from the options given below :

The correct order of first ionization enthalpy values of the following elements is : (A) O (B) N (C) Be (D) F (E) B Choose the correct answer from the options given below :

Number of elements from the following that CANNOT form compounds with valencies which match with their respective group valencies is ________. B, C, N, S, O, F, P, Al, Si

The correct order of the first ionization enthalpy is