Select the correct answer. Did an oxidation-reduction reaction occur in the reaction between copper sulfate and sodium sulfide?

CuSO4 + Na2S → CuS + Na2SO4

A.
This is a redox reaction because copper gained electrons.
B.
This is a redox reaction because sodium lost electrons.
C.
This is a redox reaction because sulfur gained electrons.
D.
This is not a redox reaction because no electrons were transferred.
E.
This is not a redox reaction because oxygen did not gain electrons.

D. This is not a redox reaction because no electrons were transferred.

Explanation:

We can check whether a reaction is a redox reaction by determining the oxidation number of each atom on both sides of the arrow.

The oxidation number does not change for any atom, so this is not a redox reaction.

Precipitation question

B. CdSO₄(aq) + K₂S(aq) → CdS(s) + K₂SO₄(aq)

Explanation:

A precipitation reaction occurs when an insoluble solid forms from the reaction of two substances in a solution.

This is the only reaction that forms a solid from two soluble reactants.

Explanation:

WHATEVEEET

"hydrogen bonding is the attraction of h atoms in the water molecule (slight + charge) to o atoms in a neighboring water molecule (slight - charge); it is a weak interatomic force. but it is still strong enough to the water molecules "stick" together."

the density of gold = 19.3 g/cm3

the relation between density and mass and volume is

density = mass / volume

given :

mass of gold = 13 g

density = 13g / volume = 19.3

volume = 13 /19.3 = 0.67 cm^3

thus volume of gold nugget = 0.67 cm^3