Which of the following groups of transition metals are known as coinage metals?

$100 \ g$ of water is heated from $30^{\circ}C$ to $50^{\circ}C$. Neglecting the slight expansion of water,the change in its internal energy is ....... $kJ$? (Specific heat of water = $4184 \ J/kg\cdot K$)

$A$ circle passes through the point $(3, 4)$ and cuts the circle $x^2 + y^2 = a^2$ orthogonally. The locus of its centre is a straight line. If the distance of this straight line from the origin is $25$,then $a^2$ is equal to

In the ground state,an element has $13$ electrons in the $M$ shell. The element is

In gel electrophoresis,the separated bands of $DNA$ are cut out and extracted from the gel piece. This step is called

$CrO_3$ dissolves in aqueous $NaOH$ to give: