Holiday homework assignment no-1

My dear students.
I hope you've enjoyed much the vacation.This is the time to return back to school homeworks.
Assignemnt -1
Paper-06
1. Beach sand is a mixture of sand and broken shells(CaCO3). CaCO3 reacts with dil.HCl to form a solution of CaCl2. Plan an investigation (stepwise procedure) to findout the % of shell material in a sample of beach sand.
2. SO2 gas is a common pollutant formed when fossil fuels burn in air. SO2 can be detected by using an acidic solution of K2Cr2O7(VI). The K2Cr2O7 solution changes colour from orange to green when a certain amount of SO2 has reacted with it.
Plan an experiment to investigate which of three different samples of coal produces most SO2.
Paper-03
1. --------------------
Healthy bones
Each tablet consists
Ca
Mg
Zn
Cu
B
-------------------

B is a non-metal with a macro molecular structure.
(i) What is the valency of B?
(ii) Predict two physical properties of B.
(iii) Name another element and a compound that have macromolecular structure element.

To be continued as assignment-02 on tomorrow.