The first one is C. Hope this helps!! If you need anymore help just message me and I will try to get back to you quickly and help in any way i can!
Answer:

Given:
Bone density = 2.0 kg/m³
Volume of bone (V) = 0.00027 m³
To Find:
Mass of an adult femur bone (m).
Explanation:

This should help
there always needs to be 2 electrons in the first shell then 8 electrons in each shell and continue till you not have any more number of electron left
Answer - B. Betelguese.
I really hope this helps!!
Answer:
B. The presence of an unbalanced force(e.g friction) causes a moving object to stop.
Explanation:
As the friction is that force that can stop the sled upon reaching the levelled surface so the option b is correct.