What type of plants are Pteridophytes?

The electrons identified by quantum numbers $n$ and $l$: $(i)$ $n = 4, l = 1$; $(ii)$ $n = 4, l = 0$; $(iii)$ $n = 3, l = 2$; $(iv)$ $n = 3, l = 1$ can be placed in order of increasing energy from the lowest to highest,as

The value of $\int_{-1}^{1} (\sqrt{1 + x + x^2} - \sqrt{1 - x + x^2}) \, dx$ is

The half-life of a radioactive element is $10 \ h$. The fraction of initial radioactivity of the element that will remain after $40 \ h$ is

Two parallel metal plates having charges $+Q$ and $-Q$ face each other at a certain distance between them. If the plates are now dipped in a kerosene oil tank,the electric field between the plates will

The energy of a photon is $3 \times 10^{-12} \ erg$. What is its wavelength in $nm$?
$(h = 6.62 \times 10^{-27} \ erg \cdot s; c = 3 \times 10^{10} \ cm/s)$