A substance undergoing thermal expansion will expand when heated, substances will mostly expand when heated but when their cold it will undergo contraction.
Answer:
hot air rises because gases expand as they heat up.When air heats up and expands,its density also increases.The warmer,less dense air effectively floats on top of the colder, dense air below it. This creates a buoyant force that causes warmer air to rise.
cold air sinks because it is heavier as its more dense ( because of closely packed molecules) soits harder for them to move and they absorb less energy. Also, gravity pulls on it more strongly.
Hope it helps :)
You must remember that oxidation number of hydrogen in acids is always +1, oxidation number of oxygen in oxides & acids is always -2... metals has always oxidation number on plus!
group NO3 comes from HNO3...and oxidation number of whole acid group is always on minus and equal to the amount of hydrogen atoms in this acid... so oxidation number of NO3 = -1
we have 2 NO3 groups so 2*(-1) = -2 and that is the reason why oxidation number of Fe in this formula must be +2... because sum of all elements always gives 0!
Now we could count of oxidation number for nitrogen... we write HNO3 and start counting from right to left:
3*(-2) from oxygens + 1 from hydrogen = -5
so nitrogen must have +5 oxidation number... because sum all in formula must be 0.
Answer:
ver explicacion
Explanation:
El elemento que tiene el número atómico 56 en la tabla periódica del bario. El bario es un elemento del grupo dos.
Se combina con el cloro para formar cloruro de bario. que tiene la fórmula BaCl2 de acuerdo con la valencia de ambos elementos.
El cloruro de bario es un compuesto iónico.
Natural selection requires variation between individuals. Mutations and reproduction increase genetic variation in a population. Natural selection occurs when environmental pressures favor certain traits that are passed on to offspring.
