Please help with question 4 and 5 please!!

Which element has the lowest electronegativity? calcium(ca) gallium(ga) selenium(se) bromine(br)

13. a covalent bond between two atoms is likely to be polar if: a. one of the atoms is much more electronegative than the other. b. the two atoms are equally electronegative. c. the two atoms are of the same element. d. the bond is part of a tetrahedrally shaped molecule. e. one atom is an anion.

Asample of water is taken and kept in a beaker in a freezer at a constant temperature of 0°c. if the system is at dynamic equilibrium, which of these statements is true? the rate of freezing is equal to the rate of melting. the rate of freezing is greater than the rate of melting. the amount of ice is greater than the amount of water. the amount of ice is equal to the amount of water.