Answer:
B, liquid to solid.
Explanation: Since heat is being released, the particles for H2O would clump up. Heat is basically being taken out.
Do you know what is meant by needed? does it mean lone pairs?
Chlorine react vigorously with hydrogen in the present of sunlight because chlorine has a great attraction for hydrogen's electron. During the reaction, chlorine and hydrogen will donate one electron each from their valence electrons which will be shared equally by both elements, thus forming a covalent bond.
