An element occupies group No.14 and period number 2 exists in different allotropic forms. One form of this element has lubricating property (A). Another form is the hardest substance (B). New allotrope of this element is named as `Buckyball' (C) and it is superconducting. Identify the element, (A) (B) and (C).

An element occupies group no.13 and period number 2 is an representative element of that group reacts with carbondioxide and forms an oxide (A). (A) reacts with CuSO_(4) give blue beads (B). Identify the element compound (A) and (B). Write the reaction.

An element occupies group No.16 and period number 2. This element on passing through silence electric discharge forms (A). (A) also reacts with lead sulphide and forms (B). (A) also reacts with BaO_(2) and forms (C). It reacts with H_(2)O_(2) and forms (D). Identify the dement (A), (B), (C) and (D).

An element occupies group number 1 and period number 2. This element burns with air and forms compound A. With water, it gives compound B, with hydrogen it forms an ionic compound C. Identify the elements, A, B and C.

An element occupies group number 2 and period number 3. This element reacts with oxygen and nitrogen to form compound A and B. It is a strong electropositive metal so it displaces Ag from AgNO_3 solution. With concentrated nitric acid, it forms compound C. Identify the element, compound A, B and C.

An element A occupies group number 17 and period number 2, is the most electronegative element. Element A reacts with another element B, Which occupies group number 17 and period number 4, to give a compound C. CompoundC undergoes sp^3 d^2 hybridisation and has octahedral structure. Identify the elements A and B and the compound C. Write the reactions.

An element (A) belonging to group number 1 and period number 3 react with dihydrogen to form an hydride (B). The element (A) reacts with the universal solvent to give a strong base (C). Identify A, Band C.

An element occupies group number 1 and period number 3. This element when exposed to air gives compound (A). The element with water forms compound (B). Which is a strong base und (A) with ammonia gives compound (C ) which is used as reducing agent in organic chemistry. The element reacts with an halogen and forms cooking salt (D). Identify A, B, C and D.

An element A occupies group number 15 and period number 3, reacts with chlorine to give compound B. The compounds B on hydrolysis gives a dibasic acid C. The compound C on heating undergoes auto oxidation and reduction to give a tribasic acid D. Identify the elements A, compounds B, C and D. Write the reactions.

An element occupies group number 15 and period number 2 reacts with hydrogen under high pressure and in the presence of a catalyst it terms a hydride (A). In presence of excess of air and in the presence of platinum it forms an oxyacid (B). Identify the element, A and B.