Questions

Fluoride deficiency is a disorder which may cause increased dental caries due to a lack of fluoride in the diet. Dental caries or tooth decay is the breakdown of dental tissues by the acidic products released by the "bacterial fermentation of dietary carbohydrates”

A seconds pendulum is a pendulum whose period is precisely two seconds i.e, one second for a swing in one direction and one second for the return swing.

The objects through which light cannot pass are called as Opaque objects. Some objects allow some light to pass through them and are called as Translucent objects. The objects which allow all the light to pass through them are called as Transparent objects.

Here in the given options Book is an example of opaque object as it does not allow light to pass through it. Water is transparent object and notebook paper and sun glasses are examples of translucent objects.

To create a simple electromagnet, you'll need a source of electricity, a conductor, and metal. Wrap insulated copper wire tightly around an iron screw or nail before connecting the wire to a battery, and watch as your new electromagnet picks up small metal objects.

IC's (Integrated Circuits) also called as Chips or Microchips whose invention allowed computers to be smaller and smaller.

Sewage treatment generally involves three stages, called primary, secondary and tertiary treatment.

Primary treatment consists of temporarily holding the sewage in a quiescent basin where heavy solids can settle to the bottom while oil, grease and lighter solids float to the surface. This removes material that will either float or readily settle out by gravity. It includes the physical processes of screening, comminution, grit removal, and sedimentation.

Secondary treatment removes the soluble organic matter that escapes primary treatment. It also removes more of the suspended solids. Removal is usually accomplished by biological processes in which microbes consume the organic impurities as food, converting them into carbon dioxide, water, and energy for their own growth and reproduction.

Tertiary treatment includes removal of nutrients such as phosphorus and nitrogen and practically all suspended and organic matter from waste water.