Name the gland that increases in size during childhood and decreases in size during adulthood. What important role does it play in case of infection ?

Placenta is very important during pregnancy. What is the role of it in embryo development ?

Bond Length: Internuclear distance between two adjacent atoms in an species is known as bond length, -Bond length depends on: i) size of the atom involved in the bond formation ii) size of the orbitals involved in the bond formation iii) Lone pair-long pair repulsion iv) Resonance v) s-character of combining orbitals with the increasing size of the atoms and atomic orbitals bond length increases. Lone pair-lone pair repulsion increases bond length (if atoms are small sized) whereas resonance can increase some bond lengths and decrease some other bond length. With increasing s-character bond length decreases, whereas with increasing multiplicity of bonds, bond length decreases. However, in some cases, bond lengths are also affected by relative position of bonds (between two similar atoms). Usually but not always with increasing bond length, bond strength (and hence bond dissociation energy) decreases. In which of the following all bonds are not equivalent?

Bond Length: Internuclear distance between two adjacent atoms in an species is known as bond length, -Bond length depends on: i) size of the atom involved in the bond formation ii) size of the orbitals involved in the bond formation iii) Lone pair-long pair repulsion iv) Resonance v) s-character of combining orbitals with the increasing size of the atoms and atomic orbitals bond length increases. Lone pair-lone pair repulsion increases bond length (if atoms are small sized) whereas resonance can increase some bond lengths and decrease some other bond length. With increasing s-character bond length decreases, whereas with increasing multiplicity of bonds, bond length decreases. However, in some cases, bond lengths are also affected by relative position of bonds (between two similar atoms). Usually but not always with increasing bond length, bond strength (and hence bond dissociation energy) decreases. The correct order of B-F bond length follows the sequence

It is not possible to measure the atomic radius precisely since the electron cloud surrounding the atom doesnot have sharp boundary. One practical approach to estimate the size of an atom of a non-metallic element is to measure the distance between two atoms when they are bound together by a single bond in a covalent molecule and then dividing by two. For metals we define the term "metallic radius" which is taken as half the internuclear distance separating the metal cores in the metallic crystal. The vander Waal's radius represents the overall size of the atoms which includes its valence shell in a nonbonded situation. It is the half of the distance between two similar atoms in separate molecules in a solid. The atomic radius decreases across a period and increases down the group. Same trends are observed in case of ionic radius. Ionic radius of the species having same number of electrons depends on the number of protons in their nuclei. The size of iso electronic species -F^(-) , Na^(+) and Mg^(2+) is effected by

It is not possible to measure the atomic radius precisely since the electron cloud surrounding the atom doesnot have sharp boundary. One practical approach to estimate the size of an atom of a non-metallic element is to measure the distance between two atoms when they are bound together by a single bond in a covalent molecule and then dividing by two. For metals we define the term "metallic radius" which is taken as half the internuclear distance separating the metal cores in the metallic crystal. The vander Waal's radius represents the overall size of the atoms which includes its valence shell in a nonbonded situation. It is the half of the distance between two similar atoms in separate molecules in a solid. The atomic radius decreases across a period and increases down the group. Same trends are observed in case of ionic radius. Ionic radius of the species having same number of electrons depends on the number of protons in their nuclei. The correct order of radii is

It is not possible to measure the atomic radius precisely since the electron cloud surrounding the atom doesnot have sharp boundary. One practical approach to estimate the size of an atom of a non-metallic element is to measure the distance between two atoms when they are bound together by a single bond in a covalent molecule and then dividing by two. For metals we define the term "metallic radius" which is taken as half the internuclear distance separating the metal cores in the metallic crystal. The vander Waal's radius represents the overall size of the atoms which includes its valence shell in a nonbonded situation. It is the half of the distance between two similar atoms in separate molecules in a solid. The atomic radius decreases across a period and increases down the group. Same trends are observed in case of ionic radius. Ionic radius of the species having same number of electrons depends on the number of protons in their nuclei. Atomic radii of the noble gases are larger than the precedent elements of the same periods because

It is not possible to measure the atomic radius precisely since the electron cloud surrounding the atom doesnot have sharp boundary. One practical approach to estimate the size of an atom of a non-metallic element is to measure the distance between two atoms when they are bound together by a single bond in a covalent molecule and then dividing by two. For metals we define the term "metallic radius" which is taken as half the internuclear distance separating the metal cores in the metallic crystal. The vander Waal's radius represents the overall size of the atoms which includes its valence shell in a nonbonded situation. It is the half of the distance between two similar atoms in separate molecules in a solid. The atomic radius decreases across a period and increases down the group. Same trends are observed in case of ionic radius. Ionic radius of the species having same number of electrons depends on the number of protons in their nuclei. Which of the following statement is correct?

It is not possible to measure the atomic radius precisely since the electron cloud surrounding the atom doesnot have sharp boundary. One practical approach to estimate the size of an atom of a non-metallic element is to measure the distance between two atoms when they are bound together by a single bond in a covalent molecule and then dividing by two. For metals we define the term "metallic radius" which is taken as half the internuclear distance separating the metal cores in the metallic crystal. The vander Waal's radius represents the overall size of the atoms which includes its valence shell in a nonbonded situation. It is the half of the distance between two similar atoms in separate molecules in a solid. The atomic radius decreases across a period and increases down the group. Same trends are observed in case of ionic radius. Ionic radius of the species having same number of electrons depends on the number of protons in their nuclei. Which one among the following sets of ions represents the collection of isoelectronic species?

For a spontaneous reaction, the free energy change must be negative. DeltaG=DeltaH-TDelaS is the enthalpy change during the reaction. T is absolute temperature, and AS is the change in entropy during the reaction. Consider a reaction such as the formation ofan oxide . M+O_(2) MO Dloxygen is used wp in the course of this reaction. Gases have a more random structure (less ordered) than liquid or solids consequently gases have a higher entropy than liquids and solids, in this reaction (entropy or randomness) decreases, hence is negative. Thus, the temperature is raised the DeltaS becomes more negative. Since, TDeltaS is subtracted in the equation, then SG becomes less negative. Thus, the free energy changes increases with the increase in temperature. The free energy changes that occur when one mole of common reactant in this case dioxygen) is we may e plotted graphically against temperature for a number of reactions of metals to their oxides. The following plot is called an Ellingham diagram for metal oxide. Understanding of Ellingham diagram is extremely important for the efficient extraction of metals. For the conversion of Ca(s) to CaO(s) which of the following represent the DeltaG vs T :

For a spontaneous reaction, the free energy change must be negative. DeltaG=DeltaH-TDeltaS is the enthalpy change during the reaction. T is absolute temperature, and AS is the change in entropy during the reaction. Consider a reaction such as the formation ofan oxide . M+O_(2) MO Dloxygen is used wp in the course of this reaction. Gases have a more random structure (less ordered) than liquid or solids consequently gases have a higher entropy than liquids and solids, in this reaction (entropy or randomness) decreases, hence is negative. Thus, the temperature is raised the DeltaS becomes more negative. Since, TDeltaS is subtracted in the equation, then SG becomes less negative. Thus, the free energy changes increases with the increase in temperature. The free energy changes that occur when one mole of common reactant in this case dioxygen) is we may e plotted graphically against temperature for a number of reactions of metals to their oxides. The following plot is called an Ellingham diagram for metal oxide. Understanding of Ellingham diagram is extremely important for the efficient extraction of metals. Free energy change of Hg and Mg for the convertion to oxides the slope of DeltaG . T has been changed above the boiling points of the given metal because