Determine whether each pair of substances forms a homogeneous solution when combined. (a) ccl4 and h2o (b) kcl and h2o (c) br2 and ccl4 (d) ch3ch2oh and h2o

1)  CCl₄ and H₂O:
                           No! Tetrachloromethane being non-polar in nature doesn't dissolve in water. Hence, when mixed they form two separate layers. Hence it doesn't give a Homogeneous Solution.

2)  KCl and H₂O:
                          Yes! Potassium Chloride when dissolved in water ionizes to produce K⁺ ions which interacts with oxygen atom of water and Cl⁻ ions which interacts with hydrogen atoms of water. Therefore, forms a Homogeneous Solution.

3)  Br₂ and CCl₄:
                        Yes! Bromine being non polar dissolves in non polar tetrachloromethane and forms a Homogeneous Solution.

4)  CH₃-CH₂-OH and H₂O:
                                         Yes: Ethanol and water forms Homogeneous Solution due to presence of stronger hydrogen bond interactions. 

The answer should be c.

assuming that your periodic table has eighteen columns, you should highlight   the four elements in the third column from the left of the table.

explanation

neutral atoms of elements after calcium contain d electrons. the energy of d orbitals of a particular main shell lies between the energy of the s and p orbitals of the next main shell. for example, electrons in the have energy higher than those in the orbital while lower than those of the orbital.

by the aufbau principle, electrons fill orbitals one at a time, starting from those of the lowest energy. the orbital is therefore filled right after orbitals and before orbitals.  

potassium has electron configuration and calcium . the s orbital of a main shell holds a maximum of two electrons. the next element would thus have the electron configuration and satisfy the requirements.

a neutral atom of the element contains three electrons on top of the most recent noble gas element. it should thus be placed in the third column of the periodic table. both scandium and yttrium would satisfy the conditions. an aufbau diagram indicates that the 4f orbital is filled before the 5d. however, it appears that exceptions exists for both lanthanum and actinium. neutral atoms of the two d-block elements also demonstrate the and should be highlighted as well.