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

In a series combination of copper and steel wires of same length and same diameter,a force is applied at one of their ends while the other end is kept fixed. The combined length is increased by $2 \ cm$. The wires will have ..........

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 $km$)

$A$ uniform wire of length $l$ and weight $w$ is suspended from the roof with a weight $W$ attached at the other end. The stress in the wire at a distance $l/3$ from the top is given by $(\frac{W}{A} + \gamma \frac{w}{A})$,where $A$ is the cross-sectional area of the wire. The value of $\gamma$ is . . . . . . .

If the breaking force for a given wire is $F$, and the thickness of the wire is doubled, then the breaking force will be:

$Assertion :$ Solids are least compressible and gases are most compressible.
$Reason :$ Solids have a definite shape and volume,but gases do not have either a definite shape or a definite volume.