The "Dawn horses" were actually not related to horses! Recent studies of fossils found that "Dawn Horses" were buried in the same rock layers as modern horses! evolutionists were shocked at first but then decided that the "Dawn horse" was related to rabbits! Now to answer your question no one really knows why they went extinct. Evolutionist believe they changed into rabbits and Creationists (people who believe God created the universe and that evolution is incorrect) believe they died out due to climate changes after the global flood of Noah.
Answer:
poisoning, breathing problems, skin rashes, allergic reactions, allergic sensitisation, cancer, and other health problems from exposure.
Explanation:
many hazardous chemicals are also classified as dangerous goods.
The fomula is NH4 (1+)
There are only two elements N and H.
As per oxidation state rules, the most electronegative element will have a negative oxidation state and the other element will have a positive oxidation state.
N is more electronative than H, so H will have a positive oxidation state and nitrogen will have a negative oxidation state.
You can also use the rule that states the hydrogen mostly has 1+ oxidation state,except when it is bonded to metals.
In conclusion the oxidation state of H in NH4 (1+) is 1+.
Now you must know that the sum of the oxidations states equals the charge of the ion, which in this case is 1+.
That implies that 4* (1+) + x = 1+
=> x = (1+) - 4(+) = 3-
Answer: the oxidation state of N is 3-, that is the option b.
3.47 x 
atoms of gold have mass of 113.44 grams.
Explanation:
Data given:
number of atoms of gold = 3.47 x
mass of the gold in given number of atoms = ?
atomic mass of gold =196.96 grams/mole
Avagadro's number = 6.022 X
from the relation,
1 mole of element contains 6.022 x atoms.
so no of moles of gold given = 
0.57 moles of gold.
from the relation:
number of moles = 
rearranging the equation,
mass = number of moles x atomic mass
mass = 0.57 x 196.96
mass = 113.44 grams
thus, 3.47 x atoms of gold have mass of 113.44 grams
