A neutral atom of potassium has 19 electrons.
Answer:

Explanation:
The formula for the velocity of the ball is

1. Velocity at time of impact

2. Velocity on rebound
The ball has enough upward velocity to reach a height of 0.86 m.

3. Acceleration

First, we have to remember the molarity formula:

Part 1:
In this case, our solute is sodium nitrate (NaNO3), and we have the mass dissolved in water, then we have to convert grams to moles. For that, we need the molecular weight:

Then, we calculate the moles present in the solution:

Now, we have the necessary data to calculate the molarity (with the solution volume of 200 mL):

The molarity of this solution equals 0.2339 M.
Part 2:
In this case, we have the same amount (in moles and mass) of sodium nitrate, but a different volume of solution, then we only have to change it:

So, the molarity of this solution is 0.1701 M.
Answer:
0.4 M
Explanation:
The process that takes place in an aqueous K₂HPO₄ solution is:
First we <u>calculate how many K₂HPO₄ moles are there in 200 mL of a 0.2 M solution</u>:
- 200 mL * 0.2 M = 40 mmol K₂HPO₄
Then we <u>convert K₂HPO₄ moles into K⁺ moles</u>, using the <em>stoichiometric coefficients</em> of the reaction above:
- 40 mmol K₂HPO₄ *
= 80 mmol K⁺
Finally we <em>divide the number of K⁺ moles by the volume</em>, to <u>calculate the molarity</u>:
- 80 mmol K⁺ / 200 mL = 0.4 M
Answer:
Argon
Explanation:
It has more electron than chlorine