Questions

The condition of blockage of the artery due to plaque deposition in the walls which can lead to stroke or heart attack is called Atherosclerosis.

Whereas,

The condition in which the stiffening or hardening of the arteries is called as Arteriosclerosis.

Semiconductors are the basic materials used in the present solid state electronic devices like diode, transistor, ICs, etc. 2. Lattice structure and the atomic structure of constituent elements decide whether a particular material will be insulator, metal or semiconductor. Semiconductors are elemental (Si, Ge) as well as compound (GaAs, CdS, etc.). Silicon, Germanium, Gallium Arsenide are semiconductors, but Quartz is an insulator.

Error is in second part. Returning means coming back to place from where you began. So, the use of back after returned becomes redundant. Without using back, the meaning remains the same. We can omit ‘back’ in part b, and use ‘returned home.’