Asolution containing a mixture of metal cations was treated with dilute hcl and no precipitate formed. next, h2s was bubbled through the acidic solution. a precipitate formed and was filtered off. then, the ph was raised to about 8 and h2s was again bubbled through the solution. a precipitate again formed and was filtered off. finally, the solution was treated with a sodium carbonate solution, which resulted in no precipitation. which metal ions were definitely present, which were definitely absent, and which may or may not have been present in the original mixture?

Explanation:

If you follow the statements carefully the only ions you can rule out as being "Definitely not present" are: Cr3+, Fe3+, and Zn2+ . The rest of the ions should be categorized under "Possibly present", as we cannot determine if any of the ions are "Definitely present".

answer: enthalpy

explanation:

for a exothermic reaction, the energy is released i.e. the energy of the products is lower than the energy of the reactants.

= enthaply

= energy of products

= energy of reactants

as , thus comes out to be negative. negative value of enthalpy shows that the reaction is exothermic.

the term hydride is commonly named after binary compounds that hydrogen forms with other elements of the periodic table. hydride compounds in general form with almost any element, except a few noble gases. the trends and properties vary according to the type of intermolecular force that bonds the elements together, the temperature, its molecular masses, and other components. hydrides are classified into three major groups, depending on what elements the hydrogen bonds to. the three major groups are covalent, ionic, and metallic hydrides. formally, hydride is known as the negative ion of a hydrogen, h-, also called a hydride ion. because of this negative charge, hydrides have reducing, or basic properties. its special characteristics will be further discussed.

explanation: