Questions

Astronomy is the study of planets and heavenly bodies. Historically, astronomy has focused on observations of heavenly bodies. It is a close cousin to astrophysics. Succinctly put, astrophysics involves the study of the physics of astronomy and concentrates on the behavior, properties and motion of objects out there.
 

Tooth Enamel is the hardest and most highly mineralized substance in the human body. It is a tissue and not a bone. This tissue has high mineral content which makes it hardest substance.

Femur and Temporal bone of the skull are the hardest bones of the human body.

The main function of input devices is to direct commands and data into computers. Computers then use their CPU to process this data and produce output.

Examples of input devices - keyboards, mouse, barcode readers, Magnetic Ink Character Readers (MICR), Optical Character Readers (OCR), touch screens, etc...

Annie Besant (1847-1933) – political reformer, women's rights activist, theosophist and Indian nationalist is known as the grand old lady of Indian nationalism.

‘Instead’ is used as an alternative or substitute and is not relevant in this context. ‘Nevertheless’ will be used as it means ‘inspite of that’. Thus, the correct formation would be, ‘This scooter is not as efficient as it used to be; nevertheless it is still a very useful machine.