Chemistry
Postulates of modern atomic theory are:
P — Atoms of an elements may not be alike.
Q — Atoms of elements combine in small whole numbers to form molecules.
R — Atoms can neither be created nor destroyed.
- Only P
- Only Q
- Only R
- Both P and Q
Answer
Only P
Reason — According to mordern atomic theory, atoms of an element may not be alike in all respects, as is seen in the case of isotopes.
Modern atomic theory states that atoms can be created and destroyed by nuclear fusion and fission and in the formation of organic compounds, the number of atoms that combine is very big such as thousands. Hence, other two statements are incorrect.
Related Questions
Two atoms are said to be isobars if they have the same:
- number of neutrons but different number of electrons.
- number of electrons but different number of neutrons.
- atomic number but different mass numbers.
- sum of protons and neutrons but the number of protons is different.
An atom is neutral, its nucleus contains:
P — Negatively charged particles.
Q — Neutral particles.
R — Positively charged particles.
- Only P
- Only Q
- Only R
- Both Q and R
An atom is electrically neutral because :
P — Electrons, protons and neutrons are equal in number.
Q — Protons are equal to neutrons.
R — Protons are equal to electrons.
- Only P
- Only Q
- Only R
- Both Q and R
Select the correct statement(s) for the diagram shown below.
P — Mg loses electrons and undergoes reduction.
Q — Cl gains electrons and undergoes reduction.
R — Mg loses electrons and undergoes oxidation.
- Only P
- Only Q
- Only R
- Both Q and R