Synapsis occurs between

The coefficient of $x^k$ in the expansion of $\frac{1-2x-x^2}{e^{-x}}$ is

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:

Which of the following oxides is different from the other three oxides?

$A$ line $L$ has intercepts $a$ and $b$ on the coordinate axes. When the coordinate axes are rotated through an angle $\alpha$ keeping the origin fixed,the same line $L$ has intercepts $p$ and $q$ on the new axes. Then

If vapour pressures of pure liquids $A$ and $B$ are $300 \ torr$ and $800 \ torr$ respectively at $25 \ ^oC$. When these two liquids are mixed at this temperature to form a solution in which mole percentage of $B$ is $92$,then the total vapour pressure is observed to be $0.95 \ atm$. Which of the following is true for this solution?