<u>Answer:</u>
Pyrite leaves behind a green-black streak when it is rubbed against an unglazed porcelain plate as a part of the streak test process.
<u>Explanation:</u>
Different minerals produce different coloured streaks when rubbed against a white ceramic or porcelain streak plate. This streak test is done to identify the mineral and distinguish the same from other minerals that look similar in colour and texture.
It must be ensured that the test is done on clean and fresh specimens of the mineral and that there must be no contaminants. Pyrite specimens are usually brass-yellow colour but it leaves a green-black streak when the streak test is done.
ΔSsys and ΔSsurr both have values larger than 0.
<h3>Entropy Change: What Is It?</h3>
- Entropy change is a phenomena that measures the evolution of randomness or disorder in a thermodynamic system.
- It has to do with how heat or enthalpy is converted during work.
- More unpredictability in a thermodynamic system indicates high entropy.
- Heat transport (delta Q) divided by temperature equals the change in entropy (delta S).
<h3>What causes variations in entropy?</h3>
- When a substance is divided into several pieces, entropy rises.
- Because the solute particles are split apart when a solution is generated, the dissolving process increases entropy.
- As the temperature rises, entropy increases.
learn more about entropy change here
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Since Oxygen is in group 16, this element has 6 valence electrons. Valence electrons like to become as stable as possible and similar to a noble gas, which has 8 electrons. You need to find an element that will transfer its atoms to the oxygen to make 8 electrons. Looking at the periodic table, Selenium is in group 16 and will have 6 valence electrons (6 + 6 = 12). This can't transfer electrons with Oxygen. Hydrogen is in group 1 with 1 valence electron (6 + 1 = 7). This can't transfer electrons with Oxygen. Strontium is in group 2 with 2 valence electrons (6 + 2 = 8). This will transfer electrons to Oxygen, making it the most stable.
The answer is O and Sr.
