Which of the following is the correct formula for copper (i) sulfate trihydrate? cuso4 · 3h2o
cuso4(h2o)3
cu2so4(h2o)3
cu2so4 · 3h2o

                   Cu₂SO₄ · 3 H₂O

                         First of all we should be interested in the oxidation number carried out by Copper atom because it can exist both in +1 and +2 state. Hence, as shown in name i.e. (I), it shows that copper is having +1 oxidation state.

                          Secondly, we should be interested in the charge carried out by sulfate ion, as it is conjugate base of sulfuric acid so, it must contain a charge of -2.

                           Therefore, to neutralize -2 charge of SO₄²⁻ ion we have to add two Cu⁺¹ ions hence,

                                             Cu₂SO₄

Furthermore, the number of water molecules are three as the word tri- specifies three.

                                        Cu₂SO₄ . 3 H₂O

                    In naming ionic compounds the positive part is named first followed by negative ion.

explanation:

venn diagram is pictorial representation with of circles showing the relation between two finite sets or things. the intersection part of two circles conveys the relation present in between those sets or things.

here in the venn diagram of sand and salt two circles represent sand and salt. but the area falling under the intersection of these circle represents the mixture of sand and salt.

so, in a venn diagram the mixture will be placed in a middle that is in between the intersection of two circles.