The formula of bleaching powder is: MCQ with Answer and Explanation

Explanation:
Isobars are atoms of different elements with the same mass number but different atomic numbers. Argon (Z=18) and Calcium (Z=20) both have a mass number of 40, making them isobars. Options A, B, and D are isotopes, as they represent the same element with different mass numbers.

Explanation:
To balance the equation: Fe atoms: 3 on right, so a=3. O atoms: 4 on right, so b=4. H atoms: 4*2=8 on left, so d=4. The balanced equation is 3Fe + 4H₂O → Fe₃O₄ + 4H₂. Thus, a=3, b=4, c=1, d=4. This ensures the law of conservation of mass is obeyed.

Explanation:
Rusting is a chemical change because iron reacts with atmospheric oxygen and moisture to form hydrated iron(III) oxide. This new compound possesses entirely different chemical properties from the original iron. The process involves the formation of new chemical bonds and cannot be easily reversed by simple physical methods.