solution:

6) Law of conservation of Mass - It states that mass is CONSERVED in any REACTION.

Mass of reactants = mass of products

Example:-

C + O₂ = CO₂

mass of carbon = 12u

mass of oxygen = 16u

In a reaction,

reactants, 12 u  + 2×16 u = 44u

products = 12 u  + 2×16 u = 44u

Thus mass of reactant = mass of product

Law of constant propotion:- it says that,  a chemical molecule will always contains the same elements in the same proportion.

Example:- water MOLECULES always contain Hydrogen and oxygen in 1:2.

7) Dalton's atomic theory:- He syas that, all elements are made up of small indivisble particles called atoms.

All atoms of the same elemnts are identical in all respects.

⊕ Limitation of dalton's atomic theory:-

1. Atoms are devisible [electron,proton and neutron]

2.All atoms are not identicals, like isotpes of carbon have diffrent mass[C¹²,C¹⁴]

8. a)Atoms:- Atom is the smallest PARTICLE on any element [while atoms furthuer can be devided in electron,proton and neutron].

b) Molecule:- Molecule is made up of More than two atoms of diffrent elemnts or same.

like- H₂ ,O₂, H₂SO₄ etc.

C) Atomic mass:- sum of Mass of total protons and neutrons is called atomic mass.

9.a) H₂O

2(1) + 16 = 18g/mol

b) H₂SO₄

2(1) + 32 + 4(16) = 98g/mol

c) HNO₃

1 + 14 + 2(16) = 47g/mol

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Amrit______