Answer:
Energy, 
Explanation:
It is required to find the energy of an electromagnetic wave with a frequency of
. The energy of a wave in terms of its frequency is given by :

= frequency of em wave

So, the energy of an electromagnetic wave is 
Answer:
a. similar properties
Explanation:
In a given column of the periodic table, the elements have similar properties.
A column on the periodic table is known as a group or family. The group is a vertical arrangement of elements on the periodic table.
Elements in the same group have the same number of valence electrons after their group number.
For example, all the elements in group 1 have one valence electron. Those in group 2 have 2 valence electrons.
The valence electrons of an atom determines its chemical properties. So, all elements in the same group have the same chemical properties.
Answer:
Precentage error = 7.23%
Explanation:
The precentage error formula is the useful method for determining precision of your experimental result
It can be calculated using :


So we get percentage error = 7.23%
Precision means how close the experimental value to the true value or theoretical value
If percentage error is large it means experimental results are deviated and there is need to check mistakes,imprecision in the experiment
If the percentage error is zero it means the experiment is perfectly done without inaccuracy
Answer:
B- A mutual attraction between the nuclei and the electrons in two different atoms