Which of the following statements is true about ions? a. anions are positively charged ions. b. cations are common among nonmetals. c. charges for ions are always written as numbers followed by a plus or minus sign. d. when an anion forms, more electrons are transferred to it.

Answer. c and d both statements are correct.

Explanation:

Statement A is incorrect because anions are the species which are negatively charged..

Statement B is incorrect because non metals generally forms anions  for example:

Statement C is correct because when we write an ion we  will first write symbol of that element than charge and then positive(cations) or negative(anions) sign. for example .

Statement D is correct because when anion is formed, electrons are gained.These number of electron depends upon the valency of that element.

When an anion forms, more electrons are transferred to it.

Anions are negatively-charged ions that is when an anion forms, more electrons are transferred to it. Anions are common among non metals.

Cations are also called positive ions. Cations are common among metals.

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the correct answer is:

a. formation of precipitation