Questions

Bond breaking is an endothermic process.

Hence, bond breakage needs an amount of energy and uses some energy based on the strength of the bond to break the bond.

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.

Egg.

Egg is to be broken if we want to use or eat it.

The Earth has four major systems or spheres. These systems are

 1. The geosphere,

 2. The hydrosphere,

 3. The atmosphere, and 

4. The biosphere.

The biosphere is the system where we belong.

Heat from the sun travels in the form of rays and are called as heat rays. This heat is called as radiation.

When heated any substance, the molecules move apart from each other. Alike in the air the molecules move apart from each other. We know that the warm air is lighter than the cool air. Since after heating air gets warmer, it floats up and the cool air comes down to occupy the warm air place.

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.