what are the answers to the questions which are there in the file attachment
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Answer:
1ANS)THE SHORT HAND METHOD OF REPRESENTING A CHEMICAL REACTION IN TERMS OF SYMBOLS AND FORMULAS OF DIFFERENT REACTANTS AND PRODUCTS IS CALLED A CHEMICAL EQUATION EG=Mg2 + O2 =Mg0 H2+O2=H20
2ANS)Given that lead nitrate, having chemical formula Pb(NO3)2 is heated in a test tube. The two observations of this chemical reaction are: (i) When lead nitrate is heated, it decomposes into lead oxide (PbO), nitrogen dioxide (NO2), and oxygen gas (O2). The type of this reaction is thermal decomposition reaction.
3ANS)(i) Before heating, it is pale green. After heating, it is brown or reddish brown. TWo observations are : (a) Change in state and colour. (b) Evolution of gas. (ii) Decomposition reaction.
4ANS)Hydrogen which is an element has its own properties due to the atoms it has like hydrogen is highly inflammable. This is the property of hydrogen atoms. Oxygen is also an element which has its own properties, which are governed by its atoms. As oxygen atoms have the property to support combustion reactions.
5ANS)Hydrogen peroxide is a highly reactive chemical. It is highly unstable and slowly decomposes when kept in presence of light. Due to this reason, hydrogen peroxide should be kept in amber coloured bottles or in opaque bottles so that little or no light passes through it.
6ANS)When 2 g of silver chloride is taken in a china dish and the china dish is placed in sunlight for some time, the white sodium chloride turns grey. This is due to the decomposition reaction through sunlight that decomposes silver chloride into silver and chloride by light.
7ANS)Decomposition reaction is represented by the digestion of food in our body.
8ANS)(i)COMBINATION REACTION CaO+H2O =Ca(OH)2 CALCIUM OXIDE + WATER = CALCIUM HYDROXIDE
(ii) calcium oxide reacts vigorously with water to produce slaked lime releasing a large amount of heat
9ans)(a) Decomposition of ferrous sulphate is an endothermic reaction because heat is absorbed during the reaction. (b) The process of dissolving sulphuric acid in water i.e., dilution of sulphuric acid) is a highly exothermic reaction. (c) The process of dissolving sodium hydroxide (a bare) in water is again a high lyexo thermic reaction. (d) Dissolution of ammonium chloride in water is an endothermic reaction as heat is absorbed during the reaction.
10ans)CuO+H2=Cu + H2O COPPER OXIDE + HYDROGEN=COPPER+WATER
11ANS)Cu +AgNo3---> Ag+Cu(No3)2
as copper is more reactive than silver
When a strip of copper metal is placed in a silver nitrate solution a grayish white deposit of silver can be seen on the copper stripe which is known as tarnishing of silver
Explanation: