What is the characteristic of an electron microscope? On which principle is it based?

$A$ proton and a $Li^{3+}$ nucleus are accelerated by the same potential. If $\lambda_{Li}$ and $\lambda_{P}$ denote the de Broglie wavelengths of $Li^{3+}$ and proton respectively,then the value of $\frac{\lambda_{Li}}{\lambda_{P}}$ is $x \times 10^{-1}$. The value of $x$ is ............
(Rounded off to the nearest integer)
(Mass of $Li^{3+} = 8.3 \times \text{mass of proton}$)

The wavelength of electrons accelerated from rest through a potential difference of $40 \, kV$ is $X \times 10^{-12} \, m$. The value of $X$ is $......$. (Nearest integer)
Given:
Mass of electron $= 9.1 \times 10^{-31} \, kg$
Charge on an electron $= 1.6 \times 10^{-19} \, C$
Planck's constant $= 6.63 \times 10^{-34} \, J \cdot s$

What is the mass of a particle with a wavelength of $3.313 \mathring{A}$ moving with a speed of $2.0 \times 10^8 \ m \ s^{-1}$?

The ratio of de-Broglie wavelength of two particles $A$ and $B$ is $2: 1$. If the velocities of $A$ and $B$ are $0.05 \ ms^{-1}$ and $0.02 \ ms^{-1}$,respectively,then the ratio of their masses $m_A: m_B$ must be

The wavelength (in $m$) of a particle of mass $1.67 \times 10^{-27} \ kg$ moving with velocity of $3.97 \times 10^6 \ m \ s^{-1}$ is: