Achange in color when two solutions are mixed together is a clue that a has taken place. physical change change in state temperature change chemical change

Chemical change  

Step-by-step explanation:

A change in colour indicates that a new substance with different properties (colour) has been formed. This is a chemical change.

A. is wrong. A physical change does not usually cause a change in colour.

B. is wrong. No new gas or solid was formed,

C. is wrong. There is a colour change, not a temperature change.

chemical change

Explanation:

A physical change is defined as a change in which shape, size of the substance alters. No new substance gets formed in these reactions.

A chemical change is defined as the change in which chemical composition alters. A new substance is formed in these reactions.

Characteristics of chemical reaction:

1. Change in color

2. formation of precipitate

3. Energy is lost or absorbed

4. A gas or bubbles are produced

Thus a change in color when two solutions are mixed together is a clue that a chemical change has taken place.

- decrease the number of plants and animals living in the water.

alkaline metals are lithium, sodium, rubidium, potassium, cesium and francium.

alkali metals have electronegativity from 0.7 to 1, lowest in periodic table of elements, which means that alkali metals (i group in periodic table) has positive oxidation number in compounds.

electronegativity is a chemical property that describes the tendency of an atom to attract a shared pair of electrons towards itself.

alkaline metals (far left in main group) have lowest ionizations energy and easy remove valence electrons,

for example, potassium is the alkali metal and has a single valence electron in the outer electron shell.

electron configuration of potassium is: ₁₉k 1s²2s²2p⁶3s²3p⁶4s¹.

they can not exist alone in nature, because they are very reactive.