Which element is responsible for the crimson red color in fireworks?

If $\frac{d}{d x}\left[(x+1)\left(x^2+1\right)\left(x^4+1\right)\left(x^8+1\right)\right] = \left(15 x^p-16 x^q+1\right)(x-1)^{-2}$,then $(p, q)$ is equal to

In which method is recombinant $DNA$ directly injected into the nucleus of an animal cell?

Which one of the following cell organelles is enclosed by a single membrane?

The work functions of metals $A$ and $B$ are in the ratio $1 : 2$. If light of frequencies $f$ and $2f$ are incident on the surfaces of $A$ and $B$ respectively,the ratio of the maximum kinetic energies of photoelectrons emitted is (given that $f > f_{0A}$ and $2f > f_{0B}$).

If $|x| < 1$,then the sum of the series $1 + 2x + 3x^2 + 4x^3 + \dots \infty$ will be