Q.Write short notes on the following:
You're viewing a preview — the full solution, concept, methods & PYQ mapping are locked.
Start your 14-day free trial to unlock the full solution →(a) Allotropy = an element existing in multiple structural forms with different physical but similar chemical properties. (b) Borax bead test = a flame test using a fused borax bead to identify coloured metal ions.
(a) Allotropy: The phenomenon in which a single element can exist in two or more different physical forms, called allotropes, which differ in their physical properties (e.g. hardness, appearance, density) due to a different arrangement/bonding pattern of their atoms or molecules, while showing broadly similar chemical properties (since they are made of the same element).
Examples: Carbon exists as diamond (tetrahedral covalent network, very hard), graphite (layered, soft, conducting), and fullerenes (cage-like molecules like C60). Phosphorus exists as white phosphorus (P4, reactive, waxy) and red phosphorus (polymeric, less reactive). Oxygen exists as O2 (dioxygen) and O3 (ozone). Sulphur exists as rhombic and monoclinic forms.
(b) Borax bead test: A simple qualitative test used to identify certain coloured (transition) metal ions in a salt. A small amount of borax, Na2B4O7·10H2O, is heated in a loop of platinum wire in a Bunsen flame. On heating, borax loses its water of crystallization and swells up, finally fusing into a clear, colourless, glassy bead of sodium metaborate and boric anhydride: .
…
Unlock everything free for 14 days
- Full step-by-step solutions
- Concept-first explanations
- Methods, shortcuts & mistakes
- PYQ mapping + timed mock tests
Full access for 14 days. No credit card required.