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: 16.7 gallon
Explanation:
Given: The car can drive 30.3 miles when 1 gallon of gasoline is used.
Distance covered = 506.3 miles
Thus for 30.3 miles, the amount of gasoline used= 1 gallon
For 506.3 miles, the amount of gasoline used=
Thus the amount of gasoline used is 16.7 gallons.
Answer:
The dam disrupts the river wildlife and ecosystem.
Explanation:
Though it is believed that using the dam as a power generation or hydroelectric power supply generates no greenhouse gases, it, however, has many disadvantages which make it deemed not suitable or sustainable for use in the contemporary time.
Majorly, the top reason why more hydroelectric dams are not built is that "the dam disrupts the river wildlife and ecosystem."
Also, it affects the water quality and other use of water for humans such as recreational use.
There is also a possible chance of dams producing methane; a greenhouse gas through the organic materials in the water that is rotting.
Answer:
1. Mass of potassium (K) = 203.32 g
2. Number of mole of As = 7.53 moles
Explanation:
1. Determination of the mass of potassium (K)
Molar mass of K = 39.1 g/mol
Number of mole of K = 5.2 moles
Mass of K =.?
Mole = mass / Molar mass
5.2 = mass of K / 39.1
Cross multiply
Mass of K = 5.2 × 39.1
Mass of potassium (K) = 203.32 g
2. Determination of the number of mole of Arsenic (As)
Molar mass of As = 74.92 g/mol
Mass of As = 563.9 g
Number of mole of As =.?
Mole = mass /Molar mass
Number of mole of As = 563.9 / 74.92
Number of mole of As = 7.53 moles