A solution contains some or all of the ions Cu2 , Al3 , K , Ca2 , Ba2 , Pb2 , and NH4 . The following tests were performed, in order, on the solution. 1. Addition of 6 M HCl produced no reaction.
2. Addition of H2S with 0.2 M HCl produced a black solid.
3. Addition of (NH4)2S produced a white solid.
4. Addition of (NH4)2HPO4 in NH3 produced no reaction.
5. The final supernatant when heated produced a purple flame.
Identify which of these ions were present in the solution, which were absent, and for which ones no conclusions can be drawn
a. Cu2+b. Al3+c. K+d. Ca2+e. Ba2+f. Pb2+g. NH4+.

answer: option (4) is the correct answer.

explanation:

areas which are at low altitudes and near the equator tend to receive direct sunlight from the sun. hence, heat energy or radiations from the sun make these areas warmer and they have warmest water.

whereas areas which are at high altitudes and away from the equator do no receive direct sunlight. hence, no direct contact from the sun makes these regions colder and thus, they have colder water.

thus, we can conclude that the statement areas at low latitudes near the equator have the warmest water because they receive the most direct sunlight best explains the relationship between an area's geography and the temperature of its surface water.

the answer would be b i believe

there is none because earth is stationary and flat.