Question

try this its tough u r great

Answer 1

this is based on concept of linear thermal expension .

use formula,
∆L =L°@∆T
where ∆L is change in length
L° is initial length
@ is coefficient of linear expension
∆T is the temperature change

now,
∆L = 12 x 11 x 10^-6 x (48-18) m
=12 x 11 x 10^-6 x 30 m
=132 x 30 x 10^-6 m
=3960 x 10^-6 m
=3.96 x 10^-3 m
=3.96 mm ≈4 mm = 0.4 cm
so, option (3) is correct