Which of the following is true when 1 m kcl is diluted to semi-molar kcl?
i. concentrated and diluted kcl contains the same number of moles

ii. water is added for dilution.

iii. kcl is added for dilution.

i and iii
i and ii
ii and iii
i, ii, and iii

The solution before dilution and after dilution contains same number of moles, and water is added for dilution.

Option B

Suppose before dilution, the solution contains x moles of KCl in Y liter of water. Now as the concentration got halved, then the solution contains x moles of KCl in 2Y kiters of solution. So the number of moles of KCl in the solution remained constant.

Again, as the solution is diluted to half of the concentration, water must have been added with the solution to make it dilute.

chemical changes occur when a substance combines with another to form a new substance, called chemical synthesis or, alternatively, chemical decomposition into two or more different substances. these processes are called chemical reactions and, in general, are not reversible except by further chemical reactions. some reactions produce heat and are called exothermic reactions and others may require heat to enable the reaction to occur, which are called endothermic reactions. understanding chemical changes is a major part of the science of chemistry.