1.the chemical change color from colorless to purple
2. A yellow gas forms
3.a brown solid forms in the bottom of the beaker
4.the temperature of the chemicals rises 15 Celsius
Explanation:
All of the options are proofs that chemical change has occurred.
A chemical change is one with the following properties:
- A new kind of matter is usually formed as seen by the gas evolution and the formation of the insoluble precipitate i.e brown solid at the bottom of the beaker.
- They are not easily reversible.
- Usually accompanied by energy changes as seen in the rise in temperature.
- Color changes can also infer chemical changes in a reaction.
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Answer:
C. hydration number
Explanation:
When we dissolve an ionic compound (a charged species) the charges can <u>interact with the water molecule</u>. In the case of <u>cations</u> (positive charges) the negative <u>dipole</u> of water (generated in the oxygen) will interact with the positive charge at the same time the <u>anions</u> (negative charges) the positive <u>dipole</u> of water (generated in the hydrogen).
The amount of water molecules that can interact with a single ion (cation or anion) is called <u>hydration number</u>. In the example, we have a hydration number of "4" for the sodium cation.
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Answer:
Moreover, increasing use of fossil fuels also causes serious environmental problems. Hence, there is a pressing need to use renewable energy sources like solar energy, wind, tide, biomass and energy from waste material. (i) it reduces the dependence on fossil fuels for energy. (ii) they donot produces pollution.
Answer:Heterogeneous mixture
Explanation:
A mixture consists of two or more components that do not chemically react together. The components of a mixture retain their individual properties. A heterogeneous mixture contains many different components that do not chemical react together.
Answer:
B) H2O
Explanation:
Compound is a pure substance composed of two or more different atoms chemically bonded to one another. Among all choices only H₂O is composed of two atoms, and other choices are composed of only one atom. H₂O is the pure substance composed of chemically bonded two atoms (hydrogen atoms and oxygen atom).
