Match the mechanism with Machine

The drawing shows a machined shaft. The purpose of providing rounded grooves at $$M$$ and $$N$$ is to

When $$3-2-1$$ principle is used to support and locate a three dimensional work-piece during machining, the number of degrees of freedom that are restricted is

Cold working produces the following effects

$$1.$$$$\,\,\,\,\,\,\,\,\,\,\,\,\,\,$$ Stress are set up in the material
$$2.$$$$\,\,\,\,\,\,\,\,\,\,\,\,\,\,$$ Grain structure get distorted
$$3.$$$$\,\,\,\,\,\,\,\,\,\,\,\,\,\,$$ Strength and hardness of the metal are decreased
$$4.$$$$\,\,\,\,\,\,\,\,\,\,\,\,\,\,$$ Surface finish is reduced