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

The ratio of the radii of nuclei $_{13}Al^{27}$ and $_{52}X^A$ is $3:5$. The number of neutrons in the nucleus of $X$ will be:

$A$ reversible engine converts one-sixth of the heat input into work. When the temperature of the sink is reduced by $62^{\circ} C$,the efficiency of the engine is doubled. The temperatures of the source and sink are:

Which of the following is the correct decreasing order of thermal stability of alkaline earth metal carbonates?

$A$ thermodynamic system is taken through the cycle $PQRS P$ process. The net work done by the system is ....... $J$. (Note: Assuming a standard $P-V$ diagram where $P$ is in $kPa$ and $V$ is in $m^3$,with vertices $P(1, 10)$,$Q(3, 10)$,$R(3, 20)$,$S(1, 20)$)

The length of the subtangent at any point $(x_1, y_1)$ on the curve $y=5^x$ is