Question 1

Who discovered the charge-to-mass ratio ($e/m$) of an electron?

Accepted Answer

J.J. Thomson determined the ratio of electrical charge ($e$) to the mass ($m$) of the electron in 1897 using a cathode ray tube.

Question 2

Which of the following species is NOT isoelectronic with $Ne$ (Atomic number = 10)?

Accepted Answer

$Cl^-$ has 18 electrons ($17 + 1$), whereas $Ne$, $O^{2-}$, $F^-$, and $Na^+$ all have 10 electrons each.

Question 3

What is the maximum number of electrons that can be accommodated in a shell with principal quantum number $n$?

Accepted Answer

The maximum number of electrons present in a principal shell with quantum number $n$ is given by the formula $2n^2$.

Question 4

Which spectral series of the hydrogen atom lies in the visible region of the electromagnetic spectrum?

Accepted Answer

The Balmer series corresponds to transitions ending at $n1 = 2$, which fall in the visible region of the electromagnetic spectrum.

Question 5

Heisenberg's uncertainty principle is mathematically represented as:

Accepted Answer

Heisenberg's uncertainty principle states that $\Delta x \cdot \Delta p \ge \frac{h}{4\pi}$, where $\Delta x$ is position uncertainty and $\Delta p$ is momentum uncertainty.

Structure of Atom