The moon phases maybe? Can I see the passage possibly?
Answer:
0.165
Explanation:
Feel free to let me know if this is wrong because I have seen the question before but cannot really remember!
There are 30 protons and 39 neutrons in the nucleus.
This must me the isotope of an element with an atomic mass close to 69 u.
The only candidates are Zn and Ga.
Zn has a zinc-69 isotope with mass 68.926 u.
Ga has a gallium -69 isotope with mass 68.925 u.
The isotope is probably

.
It has 30 protons and 39 neutrons.
Answer:
A common characteristic of most Alkali Metals is their ability to displace H2(g) from water. This is represented by their large, negative electrode potentials. In this event, the Group 1 metal is oxidized to its metal ion and water is reduced to form hydrogen gas and hydroxide ions. The general reaction of an alkali metal (M) with H2O (l) is given in the following equation:2M(s)+2H2O(l)⟶2M+(aq)+2OH−(aq)+H2(g)(1)
Explanation:
According to Henderson–Hasselbalch Equation,
pH = pKa + log [Acetate] / [Acetic Acid]
As,
pKa = -log Ka
pKa = -log (1.8 × 10⁻⁵)
pKa = 4.74
So,
pH = 4.74 + log [Acetate] / [Acetic Acid]
4.34 = 4.74 + log [Acetate] / [Acetic Acid]
4.34 - 4.74 = log [Acetate] / [Acetic Acid]
-0.40 = log [Acetate] / [Acetic Acid]
Taking Antilog on both sides,
[Acetate] / [Acetic Acid] = 0.398