Q1: The forces which meet at one point and have their lines of action in different planes are called

ANS:B - non-coplaner concurrent forces

Some imp systems of forces.

Coplanar forces - The line of action of all forces lies in the same plane,
Non-coplanar forces - The line of action of all forces do not lie in the same plane,
Collinear forces - The line of action of all forces passing through the single line,
Concurrent forces - The line of action of forces passing through the single point. Forces are not in one plane so non co-planar.
Forces meet at one point so concurrent.
So non co-planar concurrent forces. Because coplanar force means the force meet towards that point or away from that point. And force direction in different planes. So it is called as non coplanar & concurrent forces.