Out of $30$ points in a plane,$8$ of them are collinear. The number of straight lines that can be formed by joining these points is:

In an experiment with $15$ observations on $x$,the following results were available: $\sum x^2 = 2830$ and $\sum x = 170$. One observation that was $20$ was found to be wrong and was replaced by the correct value $30$. Then the corrected variance is:

If $f(x) = x^3 - 10x^2 + 200x - 10$,then

Assertion : For an isothermal reversible process $Q = -W$,i.e.,work done by the system equals the heat absorbed by the system.
Reason : Enthalpy change $(\Delta H)$ is zero for an isothermal process.

If $\alpha, \beta, \gamma$ are the roots of $x^3+2x^2-3x-1=0$,then $\alpha^{-2}+\beta^{-2}+\gamma^{-2}=$

$Assertion\,(A):$ Audio signal of frequency $10 kHz$ cannot be transmitted over long distance without modulation.

$Reason\,(R):$ Length of the antenna required $\lambda /$, should have practical value.