Give reasons for the following:- i. elemental phosphorus does not exist as `P_2` molecule ii. Noble gases are known as Inert gases.

Give reasons for the following elemental phosphorus doesnot exist as P_2 molecule:- While nitrogen exist as N_2 molecule.

Give reasons for the following:- Scandium (Z=21) does not exhibit variable oxidation state and yet it Is regarded as a transition element.

Assign reason for the following, i. Phosphorus doped silicon is a semiconductor. ii. Schottky defect lowers the density of a solid. ii. Some of the very old glass object appear slightly milky instead of being transparent.

Elements of group 18 are known as noble gases because

Explain i. Oxides of nitrogen have open chain structures while those of phosphorus have closed chain or cage structure. Why is it so? IIustrate with one structural example for each type of oxides or The oxides of phosphorus have cage strućtures but not open ones. ii. Elemental phosphorus does not exist as P_2 as N_2

Give reason for the following: On electrolysis in acidic solution, amino acids migrate towards cathode while in alkaline solution these migrate towards anode. ii) The mono amine monocarboxylic acids have two p^K values.

Consider the following statements and arrange in the order of true or false I) Group 2 elements are known as alkaline earth metal except Be II) Be has the highest standard reduction potential among group 2 members III) Mg burns with dazzling brilliance in air to give MgO and Mg (NO_(3))_(2) IV) Calcium and barium metals are used to remove air from vacuum tubes (1) TTTT (2) FFFF (3) TTFT (4) TFFT

Assign reason for the following:- Of the noble gases only xenon Is known to form well-established chemical compounds.

The incorrect statements among the following is I. NCl_(5) does not exist while PCl_(5) does II. Lead prefers to form tetravalent compounds III . The three C-O bonds are not equal in the carbonate ion IV Both O_(2)^(+) and NO are paramagnetic