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Answer 1

Long answer type Questions :-

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Question:-

(a) Give Four differences between Physical and Chemical Changes .

(b) (I) State the law of conversion of mass.

(II) What do you observe when barium chloride solution is mixed with Sodium sulphate solution.

(c) Define interconversion of State of matter .What are the two factors responsible for the change of state of matter.

(d) Write the five characteristics features of chemical change with chemical equation.

Answer:-

(a) Four differences between Physical and Chemical Changes are:-

Physical Change

• No new substance is formed
• It is a reversible change.
• The properties of constituents are retained.
• It is a temporary change.

Chemical change

• New substance is formed .
• It is a irreversible change.
• The properties of constituents are not retained.
• It is a permanent change.

(b) (I)The Law of Conversion of Mass :-

The law states that mass can neither be created nor destroyed in a chemical reaction i.e. Total masses of reactants is equal to the sum of masses of products and the masses of unreacted reactants.

(II) When barium chloride reacts with Sodium sulphate we can observe white percipitate in the form of Barium Sulphate. This is a double displacement reaction.

(c) The process by which matter changes from one state to another and back to original state, without any change in its chemical composition is called interconversion state of matter.

Two factors responsible for change of state of matter are:

• Change in Temperature.
• Change in Pressure.

(d) The five characteristics features of chemical change are:-

• Formation of a percipitate➡️ $BaCl_2_(aq) +Na_2SO_4_(aq)→BaSO_4(s) +2NaCl_(aq)$
• Change in colour ➡️ $Pb(NO_3)_2_(aq)+2KI→PbI_2(s)+2KNO_3_(aq)$
• Change in temperature➡️ $Zn(s) + H_2SO_4_(aq) → ZnSO_4_(aq) + H2$
• Change in State➡️ $NH_3+HCl→NH_4Cl$
• Evolution of Gas➡️ $H_2SO_4+Z_n→ Z_nSO_4+H_2$