D the substance is a homogeneous mixture
Answer:
In the given case, the atomic number of the given atom is 15, hence its nucleus contains 15 protons. The number of protons and electrons are the same in atom and that is what keeps it neutral. In the second case, the atomic number is 20. Hence, the atom will contain a total of 20 protons in its nucleus.
Explanation:
Standard temperature is 273 K
Standard pressure is 1 atm
We use the ideal gas equation to find out density of nitrogen gas in g/L
Ideal gas equation:
Molar mass of 
Pressure = 1 atm
Temperature = 273 K
= 1.25 g/L
Therefore, density of nitrogen gas at STP is 1.25 g/L
In your hand, the ball has higher potential energy than kinetic because it is still off of the ground but it isn't moving so there is no kinetic. As the ball rises, its potential and kinetic energy increases. At its peak, it has very high potential energy and very low kinetic energy. As it falls, the potential energy decreases but kinetic does not.
