Available Answers

1. 1.

   Choose the correct word from the choice in bracket.

   1. A covalent molecule of oxygen [¹⁶₈O] contains _____________ [one / two / three / four] electrons in the outer shell of each of the oxygen atoms, which are not involved in sharing.
   2. Molecular weight of oxygen is 32g. i.e. 1 molecule of oxygen is _____________ [64 / 16 / 32] times as heavy as ¹/₁₂th the mass of carbon atom [C¹²].
   3. Efflorescent salts on exposure to the atmosphere, change from _____________ [amorphous to crystalline / crystalline to amorphous] state.
   4. Temporary hardness in water is due to _____________ [soluble / insoluble] calcium & magnesium bicarbonates in water.
   5. In double decomposition reactions between two compounds - base & acid - to give salt & water, there is an interchange of _____________ [ions / radicals / molecules]
2. 2.

   Identify the types of reactions A to E, by matching them with the reactions (i) to (v).

   A: Displacement reaction        B: Thermal dissociation         C: Reduction reaction        D: Double decomposition reaction         E: Photochemical reaction

   1. 4AgBr           →         2Ag₂Br + Br₂
   2. Mg + 2HCl [dil.]           →         MgCl₂ + H₂
   3. Cu(OH)₂ +  H2SO₄  [dil.]    →        CuSO₄ + 2H₂O
   4. NH₄Cl           ^heat⇆ _cool    NH₃ + HCI
   5. 2FeCl₃ + H₂S          →        2FeCl₂ + 2HCl + S
3. 3.

   'Column A' gives the details of properties of certain elements in the different groups of the Periodic Table and 'Column B' - the elements of the Periodic Table. Copy and complete the table below to match the properties in 'Column A' with the elements in 'Column B'.

   Column A	Column B
   (i) Is the gaseous element in group 15 [V A] (ii) Is the liquid non-metallic element of group 17 [VIIA] (iii) Is the most electronegative element of group 17 [VIIA] (iv) Is an element of group 16 [VIA) which exists in allotropic forms (v) Has 4 electrons in its valence shell & is in group 14 [IVA]	A: Fluorine B: Sulphur C: Carbon D: Nitrogen E: Bromine

    

   Property	1	2	3	4	5
   Element

    

4. 4.

   Match the names of compounds in 'Column A' with their correct formulas from 'Column B'.

   Column A	Column B
   (i) Iron [III] chloride (ii) Iron [III] sulphate (iii)  Iron [II] chloride (iv) Iron [III] sulphide (v)  Iron [III] sulphide	A: FeCl2 B: Fe3O4 C: Fe2O3 D: FeCl3 E: FeO F: FeS	G: FeSO4 H: Fe2S3 I: FeCl J: FeS2 K: Fe2(SO4)3

5. 5.

   State the law which relates between the pressure of a gas and the volume occupied by it.

6. 6.

   At a pressure of 152 cm. Hg., a gas 'X' has a volume of 50 cc. At what pressure will the volume be 30 cc., temperature remaining constant throughout.