Help! Which chemical reaction represents a double displacement reaction?

A. 2Na + Cl2 > 2NaCl
B. 2KClO3 > 2KCI + 302
C. Zn + 2HCl > ZnCl2 + H2
D. NaOH + HCI > NaCl + H20

This chart represents the melting point of several substance. what besy explains the high melting point of the salt?

The valence of aluminum is +3, and the valence of the chlorine is -1. the formula fir the aluminum chloride is correctly written as

What is conserved in the reaction shown below? h2(g) + cl2 (g) --> 2hcl(g)a. mass onlyb. mass and moles onlyc. mass, moles, and molecules onlyd. mass, moles, molecules, and volume