Question

plz answer the following ques

Answer 1

Option C i.e [5√2+5]

Although I have provided a rough sketch but you will have to use your imagination here.

Slant height of the lateral surface of the pyramid formed by connecting centers of all the spheres
$= \sqrt{ 10^{2} - 5^{2} } = \sqrt{75}$

Height of the pyramid formed by joining the centres of all the spheres
$= \sqrt{ [ \sqrt{75}] ^{2} - 5^{2} }= \sqrt{75-25} = \sqrt{50}$

So, total height of the center of the topmost sphere from ground level
$= \sqrt{50}+5=[5 \sqrt{2}+5] units$

#If you still need any more clarification. Just tell me in comment section.

Answer 2

Ahoy!

Refer to the attachment