Copper has a face-centered cubic $(fcc)$ lattice with an interatomic spacing equal to $2.54 \ \mathring{A}$. The value of the lattice constant for this lattice is .... $\mathring{A}$ $[AIPMT \ 2005]$

For the tensile stress on the cross-section $PQRS$ to be maximum,$\theta =$ ......... $^o$

Two identical wires of rubber and iron are stretched by the same weight. The number of atoms in the iron wire will be:

The maximum possible height of a mountain on Earth is approximately (elastic limit of mountain rock $= 30 \times 10^7 \ N m^{-2}$,average density of mountain rock $= 3 \times 10^3 \ kg m^{-3}$,$g = 10 \ m s^{-2}$). (in $km$)

Match the following:

Column $I$	Column $II$
$A$. Hooke's law	$1$. Tangential strain
$B$. Shearing strain	$2$. Temporary loss of elastic property
$C$. Bulk strain	$3$. Elastic limit
$D$. Elastic fatigue	$4$. $3$ times the linear strain

$A$ light rod of length $200\,cm$ is suspended from the ceiling horizontally by means of two vertical wires of equal length tied to its ends. One of the wires is made of steel and has a cross-section of $0.1\,cm^2$,and the other is made of brass with a cross-section of $0.2\,cm^2$. At what distance from the steel wire should a weight be hung along the rod to produce equal stresses in both wires?