Questions

A star is a self luminous astronomical object and shines due to internal radiation from the enrgy sources. All stars are held together by their own gravity called Gravitational force.

Mumps : This is a swelling caused by information of parotid glands placed in front of our ear region. The inflammation is caused by a virus.

Saliva is produced by the salivary gland which helps in food digestion.

Option A) contains fluoride to harden the tooth enamel is not the function of saliva.

An invention that improved safety for railway passengers is Air brakes. With the use of air brakes using compressed air, become more effective by preventing many train accidents.

High level data models provide the concepts that are close to the way many users perceive data

Radio waves have much longer wavelengths and lower frequencies than do visible light waves. In contrast, X-rays have much shorter wavelengths and higher frequencies. 

Ultraviolet Light (UV). part of the electromagnetic spectrum that consists of waves with frequencies higher than those of visible light and lower than those of x-rays.