Answer:
Mendeleev had left the noble gases out of his periodic table.
Explanation:
Mendeleev's periodic table is pictured in the image attached to the question.
Mendeleev's table obviously lacked the noble gases. The reason for this grave omission is simple; the noble gases were not known as at the time when he formulated his periodic table. There weren't any known elements whose properties were similar to the properties of the noble gases. This would have lead him to suspect their existence.
Answer:
2.75 mol
Explanation:
Given data:
Mass of Nitrogen = 38.5 g
Moles of ammonia produced = ?
Solution:
Chemical equation:
N₂ + 3H₂ → 2NH₃
Number of moles of nitrogen:
Number of moles = mass/ molar mass
Number of moles = 38.5 g/ 28 g/mol
Number of moles = 1.375 mol
Now we will compare the moles of ammonia and nitrogen from balance chemical equation.
N₂ : NH₃
1 : 2
1.375 : 2×1.375 = 2.75 mol
Thus 2.75 moles of ammonia are produced from 38.5 g of nitrogen.
<span>S-shadows tells that the earths interior is liquid.</span>
3Na2O(at) + 2Al(NO3)3(aq) —> 6NaNO3(aq) + Al2O3(s)
This is a double replacement reaction and NaNO3 is aqueous because Na is an alkali metal, plus nitrate is in the solution. Both of these are soluble. Al2O3 is not soluble because it does not contain any element that is soluble and is hence the precipitate.
Hope this helped!
Mineral resources are solid, crystalline substances made inside the Earth. These include granite, marble, limestone and precious stones which are used for jewellery. Minerals are used to make all sorts of different things which we use every day. Energy resources are things we can use to turn into electrical power.
