Question

One of the important postulations of Dalton's atomic theory is:
1. an atom is made up of electrons, protons and neutrons
2. atom can be neither created nor destroyed
3. atoms of the same element are not alike
4. all elements are available naturally as atoms only

Answer 1

Correct Answer - Option 2 : atom can be neither created nor destroyed

Explanation:

John Dalton Postulates about atoms.

• All matter is made up of tiny, indivisible particles called atoms.
• All atoms of a specific element are identical in mass, size, and other properties. However, atoms of different element exhibit different properties and vary in mass and size.
• Atoms can neither be created nor destroyed. Furthermore, atoms cannot be divided into smaller particles.
• Atoms of different elements can combine with each other in fixed whole-number ratios in order to form compounds.
• Atoms can be rearranged, combined, or separated in chemical reactions

John Dalton raised the atomic theory that acted as an explanation of the following two laws. 

• Law of conservation of mass:
  • According to the law, mass can neither be destroyed nor created in any chemical reaction.
• Law of constant proportion/ definite proportion:
  • The laws state that in a chemical substance, the elements are always present in certain proportions by mass.
• For example:
  • Oxygen & Hydrogen are present in water in a ratio of 8:1.
  • So we will obtain 1g of hydrogen and 8g of oxygen if we decompose 9g of water.
• Atom: 
  • An atom is the smallest invisible unit of matter that constitutes a chemical element.
  • Every plasma, solid, gas & liquid, composed of ionized or neutral atoms.
  • Around 100 picometers across, atoms are extremely small. 
• Atomic theory: 
  • John Dalton discovered atomic theory.
  • As per the theory, all matter whether it is a mixture, compound, element, is consists of invisible particles called ‘atoms’.