$A$ car weighs $1800\,kg$. The distance between its front and back axles is $1.8\,m$. Its centre of gravity is $1.05\,m$ behind the front axle. Force exerted by the level ground on each front wheel is ........ $N$.

If $x y \neq 0, x+y \neq 0$ and $x^m y^n=(x+y)^{m+n}$, where $m, n \notin N$, then $\frac{d y}{d x}$ is equal to

The quantum number which explains the line spectra observed as doublets in the case of hydrogen and alkali metals and doublets and triplets in the case of alkaline earth metals is

Which one of the following statements is not correct?

Which of the following is a cyclic phosphate?

$A$ radioactive nucleus undergoes a series of decays according to the scheme:
$A \xrightarrow{\alpha} A_1 \xrightarrow{\beta} A_2 \xrightarrow{\alpha} A_3 \xrightarrow{\gamma} A_4$
If the mass number and atomic number of $A$ are $180$ and $72$ respectively,what are these numbers for $A_4$?