Chemistry Questions and Answers

Phenolphthalein is a common laboratory indicator used to detect the presence of bases in a solution. In its basic form (pH > 8.3), it turns pink or purple, indicating the presence of a base.

The correct answer is (b). The second energy level (n=2) can hold a maximum of 8 electrons. It consists of two subshells, 2s and 2p, which can hold 2 and 6 electrons, respectively.

They completely dissociate into ions in solution. Strong electrolytes are substances that fully dissociate into ions when dissolved in water or melted. As a result, they produce a high concentration of ions in the solution, allowing for efficient electrical conductivity.

The atomic number of an element is equal to the number of protons, which in this case is 8. The mass number is the total number of protons and neutrons, which is 16. To find the number of neutrons, we subtract the atomic number from the mass number:

Number of neutrons = Mass number - Atomic number
Number of neutrons = 16 - 8
Number of neutrons = 8

So, the element has 8 neutrons.

The melting and boiling points are specific physical properties of each substance and can vary depending on the nature of the substance. Different substances have different melting and boiling points, which are determined by the strength of the intermolecular forces and the molecular structure of the substance.