Which of the following best describes an alkali? A. Any substance with a pH above 7.
B. A soluble solid that forms H+ ions in a solution.
C. A soluble solid that has a pH above 7.
D. An insoluble solid that forms OH-ions in a solution.

A. Any substance with a pH above 7.

Explanation:

On the pH scale substances whose value is greater than 7 and less than 14 are termed alkali.

Acids have  a pH of less than 7 whereas neutral compounds such as water has pH of 7.

it is to be noted that an alpha particle is an helium nucleus. so it contains 2 protons 2 neutrons and has a mass number of 4. when alpha decay particles are ejected from the nucleus it gets transformed into an atom which has atomic number less than 2 and a mass number less than 4.

an equation that could represent alpha decay is radium 226 decay of alpha particle forms radon 222.

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