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Write the name.
The sensation on the retina persists for a while is
Concept: undefined >> undefined
Write the name.
The persons which are unable to distinguish between different colours
Concept: undefined >> undefined
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Right or wrong sentence.
The valency of the elements in group 2 is 1.
Concept: undefined >> undefined
Right or wrong sentence.
The elements lithium and beryllium are in the same period because their valencies are similar.
Concept: undefined >> undefined
Beryllium and calcium are alkaline earth metals.
Concept: undefined >> undefined
Right or wrong sentence.
The number of shields decreases as the calculation goes down from top to bottom.
Concept: undefined >> undefined
Right or wrong sentence.
Electro chemicals are devices that convert electrical energy into mechanical energy.
Concept: undefined >> undefined
India is the first country to discover the existence of water on the moon.
Concept: undefined >> undefined
Write an explanation.
Group
Concept: undefined >> undefined
Write an Explanation.
Persistence of vision
Concept: undefined >> undefined
Write a scientific reason.
Boron and oxygen elements are placed in the second period in periodic table.
Concept: undefined >> undefined
Write a scientific reason.
In group 2, beryllium and calcium elements, calcium is more electropositive element than beryllium.
Concept: undefined >> undefined
Complete the following chart.
| Shell | n | 2n2 | Electron holding capacity |
| K | 2 × 12 | 2 | |
| L | 2 | 8 | |
| 3 | 2 × 32 | 18 | |
| N | 4 | 2 × 42 |
Concept: undefined >> undefined
Find the period in which these elements can be placed.
4Be, 17Cl, 2He, 13Al
Concept: undefined >> undefined
Electronic configuration of element A is 2,8,1. Answer the following questions based on this information.
- What is the atomic number of element A?
- Find the group to which this element belongs.
Concept: undefined >> undefined
What is an electric motor?
Concept: undefined >> undefined
In which electric motor appliances do we use it?
Concept: undefined >> undefined
Distinguish between:
Group - Period
Concept: undefined >> undefined
Write a short note.
Moon missions
Concept: undefined >> undefined
Write name of elements, symbol, atomic number, electronic configuration of second period in modern periodic table?
Concept: undefined >> undefined
