Answer:

Explanation:
From the question we are told that:
Distance of wall from CD 
Second bright fringe 
Let
Strontium vapor laser has a wavelength \lambda= 431 nm=>431 *10^{-9}m
Generally the equation for Interference is mathematically given by

Where



Answer:
The iron atom has a positive charge, making it a cation.
Explanation:
The atom has a nucleus, where the protons and neutrons, which are the subatomic particles with the highest mass, are located. Practically all the mass of the atom is concentrated in the nucleus.Protons have a positive electrical charge, while neutrons have no charge.
Electrons move around the nucleus with other negatively charged particles.
An iron atom (Fe) has 26 protons and 20 electrons in it. That is, there are 6 more protons than electrons. As mentioned, protons are positively charged. So <u><em>the iron atom has a positive charge, making it a cation</em></u>.
Answer:14 m/s
Explanation:
Kinetic energy(ke)=175J
Momentum(M)=25kgm/s
Speed=v
Mass=m
Ke=(m x v x v)/2
175=(mv^2)/2
Cross multiply
175 x 2=mv^2
350=mv^2
Momentum=mass x velocity
25=mv
m=25/v
Substitute m=25/v in 350=mv^2
350=25/v x v^2
350=25v^2/v
v^2/v=v
350=25v
v=350/25
v=14 m/s
You may look at what group they are in
Group
1A=Group 1
2A = Group 2
3A = Group 13
4A= Group 14
5A=Group 15
6A=Group 16
7A=Group 17
The #A tells you how many valence electrons there are by the # before A. Such as Chlorine, which is in 7A, so therefore has 7 valence electrons.
Similar properties. Cause they have the same number of valence electrons