Sarah and maria mixed some iron filings with yellow sulfur powder. both iron and sulfur are elements in the periodic table. the girls used a magnet to separate the iron filings from the sulphur. next, the girls poured the two elements in a test tube and heated the mixture in a flame. the two elements melted and black smoke came out of the test tube. the two liquids seemed to combine. when the girls stopped heating the test tube, there was a shiny black solid inside. the took a magnet and held it up to the new substance but nothing happened. why?

The solid, iron sulfide, had new properties. The girls caused a synthesis reaction. Something new, a compound iron sulfide, was formed. It has properties different form its parts.

answer: option (b) is the correct answer.

explanation:

a covalent bond is formed by sharing of electrons. whereas polarity arises due to difference in electronegativity of two atoms.

therefore, more is the electronegativity of an atom which combines with the titanium, more readily it will induce a partial positive and negative charge.

thus, out of the given options fluorine is most electronegative and has an incomplete octet. therefore, it will readily combine with titanium to share the electrons and complete its octet.  

"among the transition metal elements, manganese and zinc have a slight lowering of electronegativities. the reason behind this is that the nuclear charges of these elements are slightly weaker than the other transition metal elements due to the way their valence electrons are filled up. both manganese and zinc have their valence electrons filled up to the 4th shell with 1 pair of electrons (4s2) completely occupying it. although the electrons in the 3rd shell (3d) are yet to be paired since the outer most shell is filled up, the ability of the nucleus to attract electrons is lessened. hence,   the electronegativity (or the ability to attract electrons) is lessened."