Question

Please answer fast........ (c and d)

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Answer 1

c)
1.
The following reaction occurs:
Ca(OH)2(aq) + CO2(g) → CaCO3(s) + H2O(l)
Carbon dioxide passed into lime water gives a milky solution, due to precipitation of an insoluble suspension of calcium carbonate. The milkiness disappears since calcium bicarbonate is water-soluble.
It is actually a neutralization reaction, where base is Ca(OH)2 and acid is H2CO3 and a salt CaCO3 and H2O are formed.

2.
It can be observed that green Cr2(SO4)3 will be formed.When SO2 is bubbled through acidified solution of K2Cr2O7, the orange colour of K2Cr2O7 solution turns to clean green due to formation of chromium sulphate

3.
A black colour compound is formed. The compound is lead sulphide:
Equation:
(CH3COO)2Pb(aq) + H2S(g) → PbS(s) + 2CH3COOH(aq)
This is a test for the presence of H2S in the atmosphere. A moistened strip of paper saturated with (CH3COO)2Pb is exposed to the atmosphere . The formation of a black stain on the paper confirms H2S present

4. Hydrated copper sulphate, on heating, changes from blue to white and the crystalline form changes to amorphous powder
CuSo4.5H20 → [ON HEATING] → CuSo4 + 5H20
During the reaction,Water is driven off from hydrated copper sulfate when it is heated, so the forward reaction is endothermic - energy must be transferred from the surroundings for it tohappen . The backward reaction is exothermic - energy is transferred to the surroundings when it happens.

d)
1.Iron
2.potassium
3.Sodium
4. Hydrogen sulfide(H2S) or Natural gas containing H2S.
Hydrogen sulfide has a vile odor – being responsible for the unforgettable odor of rotten eggs – and is also poisonous.

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