Which of the following forces is/are fundamental in nature?
1. Gravitational force
2. Electromagnetic forces
3. Strong and weak nuclear forces
Select the correct answer using the code given below :
A spherical shell of outer radius R and inner radius R/2 contains a solid sphere of radius R/2 (see figure). The density of the material of the solid sphere is ρ and that of the shell is ρ/2. What is the average mass density of the larger sphere thus formed?

The human eye is like a camera that has a lens with :
The relative atomic mass of boron (which exists in two isotopic forms 10B and 11B) is 10.81. What will be the abundance of 10B and 11B, respectively (consider a sample of 100 atoms)?
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