answersLogoWhite

0

primary school large then 3600mm * 1000mm

middle school large then 4000mm * 1000mm

User Avatar

Ardella Ernser

Lvl 13
2y ago

What else can I help you with?

Continue Learning about Natural Sciences

Who uses a blackboard and chalk?

I am pretty sure it's a teacher.


Why blackboard called blackboard instead it calledgreen board?

The term "blackboard" originates from the traditional color of the writing surface, which is typically black or dark gray. This color allowed for high contrast with white or colored chalk, making it easier to read from a distance. While modern boards can be green or other colors, the name "blackboard" has persisted due to historical conventions. The green board, often referred to as "greenboard," is just a variation that became popular later.


What is the attraction between unlike molecules such as chalk and blackboard?

The attraction between unlike molecules, such as chalk and a blackboard, is primarily due to electrostatic forces. When chalk is rubbed on a blackboard, it can create a transfer of electrons, leading to the buildup of static charges. This charge difference generates an attractive force between the two surfaces, allowing the chalk to adhere to the blackboard. Additionally, van der Waals forces may also play a role in the interaction between these materials.


How long does it take for water to evaporate on a blackboard?

This depends on many factors.


Explain Why blackboards are not scratched by chalk but by the sand embedded in the chalk?

Blackboards are not scratched by chalk because chalk is softer than the material from which the blackboard is constructed. Sand scratches blackboards because it is harder than the material from which a blackboard is made.