I need help on either question you can answer. Thank you god bless

1.Atomic Number (Z) = Mass Number (A) - Number of Neutrons

neutrons = mass number-atomic number

Atomic mass Cl-37= 17

Mass number Cl-37=37

Neutrons = 37-17=20

2. Mass atom X = mass isotope 1 . % + mass isotope 2.%...

3. The energy in one photon can be formulated as

f = c / λ, so :

Energy is directly proportional to frequency and inversely proportional to the wavelength

So, as the frequency of photon increases, the energy of photon increases

4. Based on answer number 3 :

A. The wavelength becomes longer, and the energy decreases

you need to take a look at the periodic system in order to sort these elements into pairs that would most likely exhibit similar chemical properties. first, you need to find elements that are found in the same group (groups are vertical in the periodic system), and then to see whether they have the same valence number. if they meet these criteria, they will have similar properties.

the first pair: ne (neon) and kr (krypton), are noble gases found in group 8

the second pair: li (lithium) and k (potassium), found in group 1

the third pair: s (sulfur) and te (tellurium), found in group 6

i believe the answer is a.