Which of the following models states that "In an atom,the positive charge is uniformly distributed and electrons are embedded into it"?

Which orbit of $Be^{+3}$ has the same orbit radius as that of the ground state of hydrogen atom?

$A$ $100 \ W$ bulb emits light of wavelength '$x$' $\mathring{A}$. What is the value of $x$,if the number of photons emitted is $2.0 \times 10^{20} \ s^{-1}$? $(h = 6.63 \times 10^{-34} \ J \cdot s, c = 3 \times 10^8 \ m \cdot s^{-1})$

The figure shows six spectral lines in an emission spectrum arising from energy level transitions. Which of the following spectral lines does not appear in the absorption spectrum?

The wavelength of $H_{\alpha}$ line of Balmer series is $X \ \mathring{A}$. What is the wavelength of $H_{\beta}$ line of Balmer series?

When a metal surface is irradiated with light of frequency $x \ Hz$,the kinetic energy of emitted photoelectrons is $z \ J$. When the same metal is irradiated with light of frequency $y \ Hz$,the kinetic energy of emitted electrons is $\frac{z}{3} \ J$. What is the threshold frequency (in $Hz$) of the metal?