Answer:
Magnesium oxide is a binary compound of magnesium and oxygen while magnesium ribbon consists only of magnesium atoms.
Explanation:
The burning of magnesium in oxygen is a chemical change. It produces magnesium oxide having greater mass than magnesium ribbon. The greater mass results from the fact that the chemical reaction has added another element to the sample- oxygen. The mass of magnesium ribbon is the mass of magnesium atoms alone but in magnesium oxide, we consider the masses of magnesium and oxygen atoms making magnesium oxide heavier than magnesium ribbon.
Answer: The final temperature of the gas is 7.58 °C.
Explanation: We are given initial and final pressure of the system and we need to find the final temperature of the system.
To calculate it, we use the equation given by Gay-Lussac.
His law states that pressure is directly related to the temperature of the gas.
![P\propto T](https://tex.z-dn.net/?f=P%5Cpropto%20T)
Or,
![\frac{P_1}{T_1}=\frac{P_2}{T_2}](https://tex.z-dn.net/?f=%5Cfrac%7BP_1%7D%7BT_1%7D%3D%5Cfrac%7BP_2%7D%7BT_2%7D)
where,
= initial pressure = 893 mmHg = 1.175atm (Conversion factor: 1atm = 760mmHg)
= initial temperature = 49.3°C = [49.3 + 273.15]K = 322.45K
= Final pressure = 778mmHg = 1.023atm
= Final temperature = ?°C
Putting values in above equation, we get:
![\frac{1.175atm}{322.45K}=\frac{1.023atm}{T_2}\\\\T_2=280.73K](https://tex.z-dn.net/?f=%5Cfrac%7B1.175atm%7D%7B322.45K%7D%3D%5Cfrac%7B1.023atm%7D%7BT_2%7D%5C%5C%5C%5CT_2%3D280.73K)
Converting Final temperature from kelvin to degree Celsius.
![T_2=280.73K=[280.73-273.15]^oC=7.58^oC](https://tex.z-dn.net/?f=T_2%3D280.73K%3D%5B280.73-273.15%5D%5EoC%3D7.58%5EoC)
Hence, the final temperature of the gas is 7.58 °C.
Answer:
<u><em>Pangaea</em></u>
<u><em>Alfred Wegner</em></u>
<u><em>plate tectonics</em></u>
Explanation:
What did Earth look like 250 million years ago? The continents of Earth were clustered together in formation that a scientist named<em> </em><u>Pangaea</u><u><em>.</em></u>The scientist that named "Pangaea" was a German scientist by the name of <u>Alfred Wegner.</u> He theorized that "Pangaea" split apart and the different landmasses, or continents, drifted to their current locations on the globe. Wegener's theories of plate movement became the basis for the development of the theory of <u>plate tectonics.</u>
One of the differences I can think of is that hydrogen is no longer listed as a group I element.
According to the mendeleev tables that I looked up, hydrogen is catorgrized as a group I element, along with Lithium, sodium, Potassium etc. However, nowadays, hydrogen does not belong to any groups in the periodic table. This is because there are arguments about whether hydrogen belongs to group I. Group I elements are all alkali metals, while hydrogen is not. However, some people says that hydrogen only have one outer shell electron so it should be in group I. Some people even say hydrogen should belong to group VII because it only needs one more electron in order to achieve the duplet of electrons.
Therefore as you may notice, hydrogen in modern periodic tables are put in the center of the periodic table on the top.