Which type of property can be observed only by changing a substance into a different substance? a. intensive property b. extensive property c. physical property d. chemical property

D. chemical property

Explanation:

Chemical property is defined as the property of a substance which is observed during a reaction where the chemical composition or identity of the substance gets changed due to formation of new substance. For example: toxicity

Physical property is defined as the property which can be measured and whose value describes the state of physical system. For Example: melting point

Extensive property is the property which depends on the amount of substance present. Example: Volume

Intensive property is the property which do not depend on the amount of substance present. Example: Density

explanation:

let the different atoms be x and y. each with four protons and same mass will be represented as follows.

mass number is number of protons + number of neutrons.

            and  

since, it is given that one has a negative charge while the other is neutral. therefore, there will be increase in number of protons and the atom will be represented as follows.

according to periodic table, mass number of beryllium is 9 and it has atomic number 4 so, the atoms will be and .  

the protons and neutrons will be located inside the nucleus whereas the electrons will be revolving around the nucleus.