$A$ piece of copper and another of germanium are cooled from room temperature to $80\,K$. Which of the following is a correct statement?

Two wires $A$ and $B$ of the same material,having radii in the ratio $1: 2$,carry currents in the ratio $4: 1$. The ratio of drift speed of electrons in $A$ and $B$ is

In the Davisson-Germer experiment, an electron beam of energy $75 \ eV$ falls normally on the surface of a crystal. If the maximum intensity is obtained at an angle of $45^{\circ}$ to the direction of the incident beam, then the inter-atomic distance in the lattice plane of the crystal will be :-............... $\mathring{A}$

Two ions having masses in the ratio $1: 1$ and charges $1: 2$ are projected into a uniform magnetic field perpendicular to the field with speeds in the ratio $2: 3$. The ratio of the radii of circular paths along which the two particles move is :

Five moles of hydrogen initially at $STP$ is compressed adiabatically so that its temperature becomes $673 \, K$. The increase in internal energy of the gas, in kilo joule is $(R=8.3 \, J/mol-K; \gamma=1.4$ for diatomic gas$)$

In Young's double slit experiment,the $y$-coordinates of the central maximum and the $10^{th}$ maximum are $2 \, cm$ and $5 \, cm$ respectively. When the $YDSE$ apparatus is immersed in a liquid of refractive index $\mu = 1.5$,what will be the corresponding $y$-coordinates?