True
Density = mass/volume
Suppose that a block has a mass of 20 g and a volume of 20 cm^3.
Density = 20 g/20 cm^3 = 1 g/cm^3
Now, you cut the block in half. The half-block has a mass of 10 g and a volume of 10 cm^3.
The density of the half-block is
Density = 10 g/10 cm^3 = 1 g/cm^3
The density <em>stays the same</em>, even though the size of the sample has changed.
This happens when pollutants emitted by cars, power plants, industrial boilers, refineries, chemical plants, and other sources chemically react in the presence of sunlight. Ozone at ground level is a harmful air pollutant, because of its effects on people and the environment, and it is the main ingredient in “smog."
Answer: periodic law.
Justification:
1) Although Mendeleev formulated the modern periodic table, ordering the elements according to their physical and chemical properties, there is not such law as Meneleev's Law.
2) The Pauli exclusion principle states that two electrons on an atom cannot have the same 4 quantum numbers, which drives to the fact that only two electrons can stay in the same orbital, each with opposite spin numbers.
3) Hund's rule states that the electrons with the same energy level will occupy the orbitals with the same spin before adding the electrons with the opposite spin.
4) Indeed the periodic law <span>states that the elements are arranged in order of increasing atomic number, and there is a
periodic repetition of their physical and chemical properties.</span>
When a neutral hydrogen atom loses an electron, a positively-charged particle should remain.
Riding your bike, you can accelerate at a rate of 2m/s^2. If you start from rest, how long will it take to reach a speed of 20m/s?
