Answer:
Either B or C. Composition or the Distance from the Earth.
<h3>
Answer:</h3>
5.71 × 10² nm
<h3>
Explanation:</h3>
The product of wavelength and frequency of a wave gives the speed of the wave.
Therefore;
Velocity of wave = Wavelength × Frequency
c = f ×λ
In our case;
Frequency = 5.25 × 10^14 Hz
Speed of light = 2.998 × 10^8m/s
But;
λ = c ÷ f
= 2.998 × 10^8m/s ÷ 5.25 × 10^14 Hz
= 5.71 × 10^-7 m
But; 1 M = 10^9 nm
Therefore;
wavelength = 5.71 × 10^-7 × 10^9
= 5.71 × 10² nm
The wavelength of light wave 5.71 × 10² nm
Electronic Configuration of elements in a period is same because If you see the electronic Configuration of elements in a period you will notice that the valence shell electrons for all elements are present in the same Shell. For example, in first period consisting of Hydrogen and Helium, both the elements' valence electrons are present in the same Shell.
Electronic Configuration of Hydrogen,
1s^1
Electronic Configuration of Helium,
1s^2
Both elements' valance electrons are present in the 1st shell
(This is just a small example to understand the concept because other periods are long but the first period is short that's why I gave the example of the first period)
Answer:
Be,Mg,Ra etc
Explanation:
It should be palced in group 2A because as it reacts with chlorine in ratio of 1:2 . It's valancy is 2 and is metal as it react with non metal donating two electrons .
one more thing it fits there orderly
