$A$ random variable $X$ has the following probability distribution:

$X = x$	$1$	$2$	$3$	$4$	$5$	$6$	$7$	$8$
$P(X = x)$	$0.15$	$0.23$	$K$	$0.10$	$0.20$	$0.08$	$0.07$	$0.05$

For the event $E = \{X \mid X \text{ is a prime number}\}$ and the event $F = \{X \mid X < 4\}$, the probability $P(E \cup F) = $

If the volume of a block of metal changes by $0.12 \%$ when it is heated through $20 ^oC$, the coefficient of linear expansion (in $^oC^{-1}$) of the metal is

At what speed should a source of sound move so that a stationary observer finds the apparent frequency equal to half of the original frequency?

The electron affinity values of elements $A, B, C$ and $D$ are respectively $-135, -60, -200$ and $-348 \ kJ \ mol^{-1}$. The outer electronic configuration of element $B$ is

Two cells $E_1$ and $E_2$ having equal e.m.f '$E$' and internal resistances $r_1$ and $r_2$ $(r_1 > r_2)$ respectively are connected in series. This combination is connected to an external resistance '$R$'. It is observed that the potential difference across the cell $E_1$ becomes zero. The value of $R$ will be

The edible part of a tomato is . . . . . . .