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Ammonium dichromate-
(NH4)2 Cr2O7
When bright orange colored ammonium dichromate is heated, it swells and decomposes violently and explosively with flashes of light. It is an exothermic reaction. Colourless and odourless water vapour and nitrogen gases are formed along with muddy grey-green solid chromium oxide(Cr2O3)

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YUVRAJ:
1) on heating the bluish green mass(Cu(No3)2) changes to a black residue which is copper oxide.
2)it gives of a reddish brown gas.
3)it also gives a gas which rekindles a glowing splinter which is oxygen .The residue is copper oxide.
Gases evolved are water vapour, nitrogen dioxide and oxygen.
Substance is copper nitrate.
This is a thermal decomposition reaction and is endothermic.

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This is a thermal decomposition reaction where Pb(NO3)2 on further heating gives out nitrogen dioxide (reddish brown gas ),oxygen (colourless)and yellow lead monoxide .The residue is lead (II)oxide (yellow)
1)Heavy white crystalline solid on stong heating crumbles with a crackling sound .
2)It gives off reddish brown gas which turns moist blue litmus paper red (NO2)
3)When a glowing wooden splinter is held in the nitrogen dioxide ,it relights showing the presence of oxygen .
4)The residue is reddish brown when hot .on cooling it changes to yellow ,fuses in glass and stains it yellow .

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This is a decomposition reaction wherein NH4Cl a white coloured odourless  solid decomposes to form NH3, a colourless gas with a pungent odour and HCl, a slightly yellow gas with a pungent odour It is an endothermic reaction.

The products formed are NH3, a base and HCl which is an acid.

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This is picture shows the sublimation of iodine crystals which are later deposited after cooling.
The violet vapour turn into crystalline state after cooling down.
When iodine crystals are heated they sublime into violet vapours that forms the sublimate on the cooler surface of the ice.

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Q2: a. Nitrogen dioxide (NO2)
b. Carbon Dioxide (CO2)
c. Hydrogen (H2)

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Q3.
a) Hydrogen Sulphide (H2S) is a colourless acidic gas that has a smell of rotten eggs. It turns moist blue litmus paper red and turns lead acetate paper into black
b) H2S is liberated by the action of dilute H2SO4 or dilute HCl on metal sulphides.

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yuvraj:
1):
a)the gas is sulphur dioxide.
b)it changes it to green
2):
b)ammonia.
a)it is basic in nature.
3):
a) ammonium solution
b) dense white fumes of ammonium chloride are formed.
c) combination reaction.
4):
a)the gas is basic.
b) sulphur dioxide.

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4. (vi) Water. Tests- It turns anhydrous white copper sulphate blue. And Cobalt chloride pink
(vii)All of the dark solid iodine will turn to purple iodine gas. This shows that iodine is sublimable.
(viii)The residue formed in E is PbO(lead oxide) It is orange yellow when hot and yellow when cold and clings to test tube.
(ix) The brown gas is NO2 (nitrogen dioxide) Test- Turns moist potassium iodide paper brown
(x)Oxygen, Test- Glowing splinter, when introduced to it, starts to burn.
(xi)A- Ammonium chloride
NH4Cl<---->NH3 + HCl
B-CuCO3
CuCO3----> CuO+ CO2
C-Copper sulphate pentahydrate
Cu2SO4.5H2O----> Cu2SO4+5H2O
D-Iodine
I2<---->I2 gas
E-Pb(NO3)2 Lead nitrate
2Pb(NO3)2---> 2PbO+ 4NO2+O2
(xii)a. Thermal decomposition: B,E
b. Thermal dissociation: A,C
c. None: D