<h3>
Answer:</h3>
Na₂S(s) → 2Na⁺(aq) + S²⁻(aq)
<h3>
Explanation:</h3>
We need to know:
<h3>What are decomposition reactions?</h3>
- Decomposition reactions are type of reactions in which a compound is broken down into two or more products.
- When a soluble substance or a compound is dissolved in water it forms an aqueous solution.
- When this happens the soluble compound such as ionic compounds ionizes to form ions.
- This is an example of decomposition reaction, since the ionic compound decomposes it ions making it.
- For example, sodium sulfide is an ionic compound that ionizes in water to form sodium and sulfide ions.
Na₂S(s) → 2Na⁺(aq) + S²⁻(aq)
Pure substances can or can not be chemically combined.
Pure substances can be either elements or compounds, but not mixture. Mixture are different substances mixing together without being chemically combined, such as air, which is a mixture of oxygen, carbon dioxide, water etc. Mixture can be separated by physical methods, like filtration or decantation.
Meanwhile, elements are the substances that cannot be further separated by any means. No matter physical or chemical methods. Examples of elements are oxygen, hydrogen, neon and all the other ones from the periodic table. Compounds are basically elements joining together, but they’re chemically combined which means their electrons (kind of subatomic particle) are either shared or given away. These elements can only be separated by chemical methods like electrolysis or heating.
Therefore, as long as the substance cannot be separated by physical methods, it can be considered as a pure substance. We can now conclude that pure substance can be (element) or can not be (compound) chemically combined.
Answer:
weighing balance/analytical balance
Graduated cylinder/buret
Explanation:
The mass of the evaporating basin could be measured using a weighing balance or an analytical balance. Both are classified as weighing scales but the analytical balance can measure the mass of objects up to 4 decimal places, thus, providing better accuracy in measurement than ordinary weighing balance that can only measure up to 2 decimal places.
In order to measure 50 cm3 of the sea water, a graduated cylinder or a buret can be used. Both equipment can measure up to the same decimal places and, thus, have virtually the same accuracy.
Answer:
Measuring distances to stars through stellar parallax. Measuring distances to stars through the moving cluster method. Astronomers measure the temperature of a star by looking at the star's color and its spectrum. The apparent brightness of a star tells how bright it seems to us
Explanation:
A. good conductors - copper, aluminium
b. fair conductors - carbon,human body
c. insulator - paper, wood
