Questions

Indonesia

The substances in which two or more atoms are attached together are called as molecular substances. 

Properties of molecular substances ::

1. Molecular substances are bonded with covalent bonds

2. Bad heat conductivity

3. Bad electrical conductivity

4. Have low melting points.

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.